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authorTakashi Iwai <tiwai@suse.de>2017-06-22 16:29:09 +0200
committerTakashi Iwai <tiwai@suse.de>2017-06-22 16:29:09 +0200
commitd11a83a49bb73e0be5a91604b6e0f01e7e08a597 (patch)
treec8a2be41f4d7273ca95ebb938f586366162d31b6
parent8cd473db02c2575c90e2586406a9886e32f51ca2 (diff)
parentf276e25bf500ed3efb34e28102400822bf06edb2 (diff)
Merge branch '/users/mhocko/SLE12-SP2/bnc1039348' into SLE12-SP2rpm-4.4.59-92.24
Pull revised stack-clash fixes from Michal Hocko (CVE-2017-1000364 bsc#1045340 bsc#1039348)
-rw-r--r--patches.fixes/0001-mm-enlarge-stack-guard-gap.patch471
-rw-r--r--patches.fixes/0002-mm-do-not-collapse-stack-gap-into-THP.patch53
-rw-r--r--patches.fixes/mm-fix-new-crash-in-unmapped_area_topdown.patch54
-rw-r--r--patches.fixes/mm-larger-stack-guard-gap-between-vmas.patch859
-rw-r--r--series.conf5
5 files changed, 916 insertions, 526 deletions
diff --git a/patches.fixes/0001-mm-enlarge-stack-guard-gap.patch b/patches.fixes/0001-mm-enlarge-stack-guard-gap.patch
deleted file mode 100644
index 849d5aabf1..0000000000
--- a/patches.fixes/0001-mm-enlarge-stack-guard-gap.patch
+++ /dev/null
@@ -1,471 +0,0 @@
-From f33ef973615afd338cacee0e86e08325ce245806 Mon Sep 17 00:00:00 2001
-From: Michal Hocko <mhocko@suse.com>
-Date: Fri, 12 May 2017 09:09:30 +0200
-Subject: [PATCH 1/2] mm: enlarge stack guard gap
-Patch-mainline: not yet (security@kernel.org discussion pending)
-References: bnc#1039348, CVE-2017-1000364
-
-Stack guard page is a useful feature to reduce a risk of stack smashing
-into a different mapping. We have been using a single page gap which
-is sufficient to prevent having stack adjacent to a different mapping.
-But this seems to be insufficient in the light of the stack usage in
-the userspace. E.g. glibc uses as large as 64kB alloca() in many
-commonly used functions. This will become especially dangerous for suid
-binaries and the default no limit for the stack size limit because those
-applications can be tricked to consume a large portion of the stack and
-a single glibc call could jump over the guard page. These attacks are
-not theoretical, unfortunatelly.
-
-Make those attacks less probable by increasing the stack guard gap
-to 1MB (on systems with 4k pages but make it depend on the page size
-because systems with larger base pages might cap stack allocations in
-the PAGE_SIZE units) which should cover larger alloca() and VLA stack
-allocations. It is obviously not a full fix because the problem is
-somehow inherent but it should reduce attack space a lot. One could
-argue that the gap size should be configurable from the userspace but
-that can be done later on top when somebody finds that the new 1MB is
-not suitable or even wrong for some special case applications.
-
-Implementation wise, get rid of check_stack_guard_page and move all the
-guard page specific code to expandable_stack_area which always tries to
-guarantee the gap. do_anonymous_page then just calls expand_stack. Also
-get rid of stack_guard_page_{start,end} and replace them with
-stack_guard_area to handle stack population and /proc/<pid>/[s]maps.
-
-This should clean up the code which is quite scattered currently
-and therefore justify the change.
-
-Todo: ia64 page fault handling calls expand_upwards explicitly for
-register store. Do we need a gap there as well?
-
-Signed-off-by: Michal Hocko <mhocko@suse.com>
-
----
- arch/ia64/mm/fault.c | 2
- fs/exec.c | 3 -
- fs/proc/task_mmu.c | 11 ++-
- include/linux/mm.h | 40 +++----------
- mm/gup.c | 4 -
- mm/memory.c | 37 +-----------
- mm/mmap.c | 152 +++++++++++++++++++++++++++++++++++++++++----------
- 7 files changed, 146 insertions(+), 103 deletions(-)
-
---- a/arch/ia64/mm/fault.c
-+++ b/arch/ia64/mm/fault.c
-@@ -224,7 +224,7 @@ retry:
- */
- if (address > vma->vm_end + PAGE_SIZE - sizeof(long))
- goto bad_area;
-- if (expand_upwards(vma, address))
-+ if (expand_upwards(vma, address, 0))
- goto bad_area;
- }
- goto good_area;
---- a/fs/exec.c
-+++ b/fs/exec.c
-@@ -196,7 +196,7 @@ static struct page *get_arg_page(struct
-
- #ifdef CONFIG_STACK_GROWSUP
- if (write) {
-- ret = expand_downwards(bprm->vma, pos);
-+ ret = expand_downwards(bprm->vma, pos, 0);
- if (ret < 0)
- return NULL;
- }
-@@ -210,6 +210,7 @@ static struct page *get_arg_page(struct
- unsigned long size = bprm->vma->vm_end - bprm->vma->vm_start;
- struct rlimit *rlim;
-
-+ size -= stack_guard_gap;
- acct_arg_size(bprm, size / PAGE_SIZE);
-
- /*
---- a/fs/proc/task_mmu.c
-+++ b/fs/proc/task_mmu.c
-@@ -307,11 +307,14 @@ show_map_vma(struct seq_file *m, struct
-
- /* We don't show the stack guard page in /proc/maps */
- start = vma->vm_start;
-- if (stack_guard_page_start(vma, start))
-- start += PAGE_SIZE;
- end = vma->vm_end;
-- if (stack_guard_page_end(vma, end))
-- end -= PAGE_SIZE;
-+ if (vma->vm_flags & VM_GROWSDOWN) {
-+ if (stack_guard_area(vma, start))
-+ start += stack_guard_gap;
-+ } else if (vma->vm_flags & VM_GROWSUP) {
-+ if (stack_guard_area(vma, end))
-+ end -= stack_guard_gap;
-+ }
-
- seq_setwidth(m, 25 + sizeof(void *) * 6 - 1);
- seq_printf(m, "%08lx-%08lx %c%c%c%c %08llx %02x:%02x %lu ",
---- a/include/linux/mm.h
-+++ b/include/linux/mm.h
-@@ -1280,39 +1280,11 @@ int clear_page_dirty_for_io(struct page
-
- int get_cmdline(struct task_struct *task, char *buffer, int buflen);
-
--/* Is the vma a continuation of the stack vma above it? */
--static inline int vma_growsdown(struct vm_area_struct *vma, unsigned long addr)
--{
-- return vma && (vma->vm_end == addr) && (vma->vm_flags & VM_GROWSDOWN);
--}
--
- static inline bool vma_is_anonymous(struct vm_area_struct *vma)
- {
- return !vma->vm_ops;
- }
-
--static inline int stack_guard_page_start(struct vm_area_struct *vma,
-- unsigned long addr)
--{
-- return (vma->vm_flags & VM_GROWSDOWN) &&
-- (vma->vm_start == addr) &&
-- !vma_growsdown(vma->vm_prev, addr);
--}
--
--/* Is the vma a continuation of the stack vma below it? */
--static inline int vma_growsup(struct vm_area_struct *vma, unsigned long addr)
--{
-- return vma && (vma->vm_start == addr) && (vma->vm_flags & VM_GROWSUP);
--}
--
--static inline int stack_guard_page_end(struct vm_area_struct *vma,
-- unsigned long addr)
--{
-- return (vma->vm_flags & VM_GROWSUP) &&
-- (vma->vm_end == addr) &&
-- !vma_growsup(vma->vm_next, addr);
--}
--
- int vma_is_stack_for_task(struct vm_area_struct *vma, struct task_struct *t);
-
- extern unsigned long move_page_tables(struct vm_area_struct *vma,
-@@ -2034,16 +2006,22 @@ void page_cache_async_readahead(struct a
- pgoff_t offset,
- unsigned long size);
-
-+extern unsigned long stack_guard_gap;
- /* Generic expand stack which grows the stack according to GROWS{UP,DOWN} */
- extern int expand_stack(struct vm_area_struct *vma, unsigned long address);
-+extern int stack_guard_area(struct vm_area_struct *vma, unsigned long address);
-
- /* CONFIG_STACK_GROWSUP still needs to to grow downwards at some places */
- extern int expand_downwards(struct vm_area_struct *vma,
-- unsigned long address);
-+ unsigned long address, unsigned long gap);
-+unsigned long expandable_stack_area(struct vm_area_struct *vma,
-+ unsigned long address, unsigned long *gap);
-+
- #if VM_GROWSUP
--extern int expand_upwards(struct vm_area_struct *vma, unsigned long address);
-+extern int expand_upwards(struct vm_area_struct *vma,
-+ unsigned long address, unsigned long gap);
- #else
-- #define expand_upwards(vma, address) (0)
-+ #define expand_upwards(vma, address, gap) (0)
- #endif
-
- /* Look up the first VMA which satisfies addr < vm_end, NULL if none. */
---- a/mm/gup.c
-+++ b/mm/gup.c
-@@ -313,9 +313,7 @@ static int faultin_page(struct task_stru
- if ((*flags & (FOLL_POPULATE | FOLL_MLOCK)) == FOLL_MLOCK)
- return -ENOENT;
- /* For mm_populate(), just skip the stack guard page. */
-- if ((*flags & FOLL_POPULATE) &&
-- (stack_guard_page_start(vma, address) ||
-- stack_guard_page_end(vma, address + PAGE_SIZE)))
-+ if ((*flags & FOLL_POPULATE) && stack_guard_area(vma, address))
- return -ENOENT;
- if (*flags & FOLL_WRITE)
- fault_flags |= FAULT_FLAG_WRITE;
---- a/mm/memory.c
-+++ b/mm/memory.c
-@@ -2666,39 +2666,7 @@ out_release:
- return ret;
- }
-
--/*
-- * This is like a special single-page "expand_{down|up}wards()",
-- * except we must first make sure that 'address{-|+}PAGE_SIZE'
-- * doesn't hit another vma.
-- */
--static inline int check_stack_guard_page(struct vm_area_struct *vma, unsigned long address)
--{
-- address &= PAGE_MASK;
-- if ((vma->vm_flags & VM_GROWSDOWN) && address == vma->vm_start) {
-- struct vm_area_struct *prev = vma->vm_prev;
--
-- /*
-- * Is there a mapping abutting this one below?
-- *
-- * That's only ok if it's the same stack mapping
-- * that has gotten split..
-- */
-- if (prev && prev->vm_end == address)
-- return prev->vm_flags & VM_GROWSDOWN ? 0 : -ENOMEM;
--
-- return expand_downwards(vma, address - PAGE_SIZE);
-- }
-- if ((vma->vm_flags & VM_GROWSUP) && address + PAGE_SIZE == vma->vm_end) {
-- struct vm_area_struct *next = vma->vm_next;
--
-- /* As VM_GROWSDOWN but s/below/above/ */
-- if (next && next->vm_start == address + PAGE_SIZE)
-- return next->vm_flags & VM_GROWSUP ? 0 : -ENOMEM;
--
-- return expand_upwards(vma, address + PAGE_SIZE);
-- }
-- return 0;
--}
-+
-
- /*
- * We enter with non-exclusive mmap_sem (to exclude vma changes,
-@@ -2721,7 +2689,8 @@ static int do_anonymous_page(struct mm_s
- return VM_FAULT_SIGBUS;
-
- /* Check if we need to add a guard page to the stack */
-- if (check_stack_guard_page(vma, address) < 0)
-+ if ((vma->vm_flags & (VM_GROWSDOWN|VM_GROWSUP)) &&
-+ expand_stack(vma, address) < 0)
- return VM_FAULT_SIGSEGV;
-
- /* Use the zero-page for reads */
---- a/mm/mmap.c
-+++ b/mm/mmap.c
-@@ -2099,7 +2099,8 @@ find_vma_prev(struct mm_struct *mm, unsi
- * update accounting. This is shared with both the
- * grow-up and grow-down cases.
- */
--static int acct_stack_growth(struct vm_area_struct *vma, unsigned long size, unsigned long grow)
-+static int acct_stack_growth(struct vm_area_struct *vma, unsigned long size, unsigned long grow,
-+ unsigned long gap)
- {
- struct mm_struct *mm = vma->vm_mm;
- struct rlimit *rlim = current->signal->rlim;
-@@ -2112,7 +2113,7 @@ static int acct_stack_growth(struct vm_a
- /* Stack limit test */
- actual_size = size;
- if (size && (vma->vm_flags & (VM_GROWSUP | VM_GROWSDOWN)))
-- actual_size -= PAGE_SIZE;
-+ actual_size -= gap;
- if (actual_size > READ_ONCE(rlim[RLIMIT_STACK].rlim_cur))
- return -ENOMEM;
-
-@@ -2148,7 +2149,7 @@ static int acct_stack_growth(struct vm_a
- * PA-RISC uses this for its stack; IA64 for its Register Backing Store.
- * vma is the last one with address > vma->vm_end. Have to extend vma.
- */
--int expand_upwards(struct vm_area_struct *vma, unsigned long address)
-+int expand_upwards(struct vm_area_struct *vma, unsigned long address, unsigned long gap)
- {
- struct mm_struct *mm = vma->vm_mm;
- int error = 0;
-@@ -2156,12 +2157,6 @@ int expand_upwards(struct vm_area_struct
- if (!(vma->vm_flags & VM_GROWSUP))
- return -EFAULT;
-
-- /* Guard against wrapping around to address 0. */
-- if (address < PAGE_ALIGN(address+4))
-- address = PAGE_ALIGN(address+4);
-- else
-- return -ENOMEM;
--
- /* We must make sure the anon_vma is allocated. */
- if (unlikely(anon_vma_prepare(vma)))
- return -ENOMEM;
-@@ -2182,7 +2177,7 @@ int expand_upwards(struct vm_area_struct
-
- error = -ENOMEM;
- if (vma->vm_pgoff + (size >> PAGE_SHIFT) >= vma->vm_pgoff) {
-- error = acct_stack_growth(vma, size, grow);
-+ error = acct_stack_growth(vma, size, grow, gap);
- if (!error) {
- /*
- * vma_gap_update() doesn't support concurrent
-@@ -2224,7 +2219,7 @@ int expand_upwards(struct vm_area_struct
- * vma is the first one with address < vma->vm_start. Have to extend vma.
- */
- int expand_downwards(struct vm_area_struct *vma,
-- unsigned long address)
-+ unsigned long address, unsigned long gap)
- {
- struct mm_struct *mm = vma->vm_mm;
- int error;
-@@ -2254,7 +2249,7 @@ int expand_downwards(struct vm_area_stru
-
- error = -ENOMEM;
- if (grow <= vma->vm_pgoff) {
-- error = acct_stack_growth(vma, size, grow);
-+ error = acct_stack_growth(vma, size, grow, gap);
- if (!error) {
- /*
- * vma_gap_update() doesn't support concurrent
-@@ -2289,29 +2284,72 @@ int expand_downwards(struct vm_area_stru
- return error;
- }
-
-+/* enforced gap between the expanding stack and other mappings. */
-+unsigned long stack_guard_gap = 256UL<<PAGE_SHIFT;
-+
- /*
- * Note how expand_stack() refuses to expand the stack all the way to
- * abut the next virtual mapping, *unless* that mapping itself is also
-- * a stack mapping. We want to leave room for a guard page, after all
-+ * a stack mapping. We want to leave room for a guard area, after all
- * (the guard page itself is not added here, that is done by the
- * actual page faulting logic)
-- *
-- * This matches the behavior of the guard page logic (see mm/memory.c:
-- * check_stack_guard_page()), which only allows the guard page to be
-- * removed under these circumstances.
- */
- #ifdef CONFIG_STACK_GROWSUP
-+unsigned long expandable_stack_area(struct vm_area_struct *vma,
-+ unsigned long address, unsigned long *gap)
-+{
-+ struct vm_area_struct *next = vma->vm_next;
-+ unsigned long guard_gap = stack_guard_gap;
-+ unsigned long guard_addr;
-+
-+ address = ALIGN(address, PAGE_SIZE);;
-+ if (!next)
-+ goto out;
-+
-+ if (next->vm_flags & VM_GROWSUP) {
-+ guard_gap = min(guard_gap, next->vm_start - address);
-+ goto out;
-+ }
-+
-+ if (next->vm_start - address < guard_gap)
-+ return -ENOMEM;
-+out:
-+ if (TASK_SIZE - address < guard_gap)
-+ guard_gap = TASK_SIZE - address;
-+ guard_addr = address + guard_gap;
-+ *gap = guard_gap;
-+
-+ return guard_addr;
-+}
-+
- int expand_stack(struct vm_area_struct *vma, unsigned long address)
- {
-+ unsigned long gap;
-+
-+ address = expandable_stack_area(vma, address, &gap);
-+ if (IS_ERR_VALUE(address))
-+ return -ENOMEM;
-+ return expand_upwards(vma, address, gap);
-+}
-+
-+int stack_guard_area(struct vm_area_struct *vma, unsigned long address)
-+{
- struct vm_area_struct *next;
-
-- address &= PAGE_MASK;
-+ if (!(vma->vm_flags & VM_GROWSUP))
-+ return 0;
-+
-+ /*
-+ * strictly speaking there is a guard gap between disjoint stacks
-+ * but the gap is not canonical (it might be smaller) and it is
-+ * reasonably safe to assume that we can ignore that gap for stack
-+ * POPULATE or /proc/<pid>[s]maps purposes
-+ */
- next = vma->vm_next;
-- if (next && next->vm_start == address + PAGE_SIZE) {
-- if (!(next->vm_flags & VM_GROWSUP))
-- return -ENOMEM;
-- }
-- return expand_upwards(vma, address);
-+ if (next && next->vm_flags & VM_GROWSUP)
-+ return 0;
-+
-+ return vma->vm_end - address <= stack_guard_gap;
- }
-
- struct vm_area_struct *
-@@ -2330,17 +2368,73 @@ find_extend_vma(struct mm_struct *mm, un
- return prev;
- }
- #else
-+unsigned long expandable_stack_area(struct vm_area_struct *vma,
-+ unsigned long address, unsigned long *gap)
-+{
-+ struct vm_area_struct *prev = vma->vm_prev;
-+ unsigned long guard_gap = stack_guard_gap;
-+ unsigned long guard_addr;
-+
-+ address &= PAGE_MASK;
-+ if (!prev)
-+ goto out;
-+
-+ /*
-+ * Is there a mapping abutting this one below?
-+ *
-+ * That's only ok if it's the same stack mapping
-+ * that has gotten split or there is sufficient gap
-+ * between mappings
-+ */
-+ if (prev->vm_flags & VM_GROWSDOWN) {
-+ guard_gap = min(guard_gap, address - prev->vm_end);
-+ goto out;
-+ }
-+
-+ if (address - prev->vm_end < guard_gap)
-+ return -ENOMEM;
-+
-+out:
-+ /* make sure we won't underflow */
-+ if (address < mmap_min_addr)
-+ return -ENOMEM;
-+ if (address - mmap_min_addr < guard_gap)
-+ guard_gap = address - mmap_min_addr;
-+
-+ guard_addr = address - guard_gap;
-+ *gap = guard_gap;
-+
-+ return guard_addr;
-+}
-+
- int expand_stack(struct vm_area_struct *vma, unsigned long address)
- {
-+ unsigned long gap;
-+
-+ address = expandable_stack_area(vma, address, &gap);
-+ if (IS_ERR_VALUE(address))
-+ return -ENOMEM;
-+ return expand_downwards(vma, address, gap);
-+}
-+
-+int stack_guard_area(struct vm_area_struct *vma, unsigned long address)
-+{
- struct vm_area_struct *prev;
-
-- address &= PAGE_MASK;
-+ if (!(vma->vm_flags & VM_GROWSDOWN))
-+ return 0;
-+
-+ /*
-+ * strictly speaking there is a guard gap between disjoint stacks
-+ * but the gap is not canonical (it might be smaller) and it is
-+ * reasonably safe to assume that we can ignore that gap for stack
-+ * POPULATE or /proc/<pid>[s]maps purposes
-+ */
- prev = vma->vm_prev;
-- if (prev && prev->vm_end == address) {
-- if (!(prev->vm_flags & VM_GROWSDOWN))
-- return -ENOMEM;
-- }
-- return expand_downwards(vma, address);
-+ if (prev && prev->vm_flags & VM_GROWSDOWN)
-+ return 0;
-+
-+ return address - vma->vm_start < stack_guard_gap;
- }
-
- struct vm_area_struct *
diff --git a/patches.fixes/0002-mm-do-not-collapse-stack-gap-into-THP.patch b/patches.fixes/0002-mm-do-not-collapse-stack-gap-into-THP.patch
deleted file mode 100644
index 0a8aa5e6d0..0000000000
--- a/patches.fixes/0002-mm-do-not-collapse-stack-gap-into-THP.patch
+++ /dev/null
@@ -1,53 +0,0 @@
-From 607215cfdd1a14871f621082ffc9448778991372 Mon Sep 17 00:00:00 2001
-From: Michal Hocko <mhocko@suse.com>
-Date: Thu, 25 May 2017 08:12:42 +0200
-Subject: [PATCH 2/2] mm: do not collapse stack gap into THP
-Patch-mainline: not yet (security@kernel.org discussion pending)
-References: bnc#1039348, CVE-2017-1000364
-
-Oleg has noticed that khugepaged will happilly collapse stack vma (as
-long as it is not an early stack - see is_vma_temporary_stack) and
-it might effectively remove the stack gap area as well because a larger
-part of the stack vma is usually populated. The same applies to the
-page fault handler.
-
-Fix this by checking stack_guard_area when revalidating a VMA
-in hugepage_vma_revalidate. We do not want to hook/replace
-is_vma_temporary_stack() check because THP might be still useful for
-stack, all we need is excluding the gap from collapsing into a THP.
-
-Also check the to-be-created THP in do_huge_pmd_anonymous_page to
-make sure it is completely outside of the gap area because we we could
-create THP covering the gap area.
-
-Noticed-by: Oleg Nesterov <oleg@redhat.com>
-Signed-off-by: Michal Hocko <mhocko@suse.com>
-
----
- mm/huge_memory.c | 8 ++++++++
- 1 file changed, 8 insertions(+)
-
---- a/mm/huge_memory.c
-+++ b/mm/huge_memory.c
-@@ -846,6 +846,9 @@ int do_huge_pmd_anonymous_page(struct mm
-
- if (haddr < vma->vm_start || haddr + HPAGE_PMD_SIZE > vma->vm_end)
- return VM_FAULT_FALLBACK;
-+ if (stack_guard_area(vma, haddr) ||
-+ stack_guard_area(vma, haddr + HPAGE_PMD_SIZE))
-+ return VM_FAULT_FALLBACK;
- if (unlikely(anon_vma_prepare(vma)))
- return VM_FAULT_OOM;
- if (unlikely(khugepaged_enter(vma, vma->vm_flags)))
-@@ -2591,6 +2594,11 @@ static void collapse_huge_page(struct mm
- goto out;
- if (!hugepage_vma_check(vma))
- goto out;
-+
-+ /* never try to collapse stack gap */
-+ if (stack_guard_area(vma, hstart) || stack_guard_area(vma, hend))
-+ goto out;
-+
- pmd = mm_find_pmd(mm, address);
- if (!pmd)
- goto out;
diff --git a/patches.fixes/mm-fix-new-crash-in-unmapped_area_topdown.patch b/patches.fixes/mm-fix-new-crash-in-unmapped_area_topdown.patch
new file mode 100644
index 0000000000..5774295631
--- /dev/null
+++ b/patches.fixes/mm-fix-new-crash-in-unmapped_area_topdown.patch
@@ -0,0 +1,54 @@
+From f4cb767d76cf7ee72f97dd76f6cfa6c76a5edc89 Mon Sep 17 00:00:00 2001
+From: Hugh Dickins <hughd@google.com>
+Date: Tue, 20 Jun 2017 02:10:44 -0700
+Subject: [PATCH] mm: fix new crash in unmapped_area_topdown()
+Git-commit: f4cb767d76cf7ee72f97dd76f6cfa6c76a5edc89
+Patch-mainline: 4.12-rc7
+References: bnc#1039348
+
+Trinity gets kernel BUG at mm/mmap.c:1963! in about 3 minutes of
+mmap testing. That's the VM_BUG_ON(gap_end < gap_start) at the
+end of unmapped_area_topdown(). Linus points out how MAP_FIXED
+(which does not have to respect our stack guard gap intentions)
+could result in gap_end below gap_start there. Fix that, and
+the similar case in its alternative, unmapped_area().
+
+Cc: stable@vger.kernel.org
+Fixes: 1be7107fbe18 ("mm: larger stack guard gap, between vmas")
+Reported-by: Dave Jones <davej@codemonkey.org.uk>
+Debugged-by: Linus Torvalds <torvalds@linux-foundation.org>
+Signed-off-by: Hugh Dickins <hughd@google.com>
+Acked-by: Michal Hocko <mhocko@suse.com>
+Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
+
+---
+ mm/mmap.c | 6 ++++--
+ 1 file changed, 4 insertions(+), 2 deletions(-)
+
+diff --git a/mm/mmap.c b/mm/mmap.c
+index 8e07976d5e47..290b77d9a01e 100644
+--- a/mm/mmap.c
++++ b/mm/mmap.c
+@@ -1817,7 +1817,8 @@ unsigned long unmapped_area(struct vm_unmapped_area_info *info)
+ /* Check if current node has a suitable gap */
+ if (gap_start > high_limit)
+ return -ENOMEM;
+- if (gap_end >= low_limit && gap_end - gap_start >= length)
++ if (gap_end >= low_limit &&
++ gap_end > gap_start && gap_end - gap_start >= length)
+ goto found;
+
+ /* Visit right subtree if it looks promising */
+@@ -1920,7 +1921,8 @@ unsigned long unmapped_area_topdown(struct vm_unmapped_area_info *info)
+ gap_end = vm_start_gap(vma);
+ if (gap_end < low_limit)
+ return -ENOMEM;
+- if (gap_start <= high_limit && gap_end - gap_start >= length)
++ if (gap_start <= high_limit &&
++ gap_end > gap_start && gap_end - gap_start >= length)
+ goto found;
+
+ /* Visit left subtree if it looks promising */
+--
+2.11.0
+
diff --git a/patches.fixes/mm-larger-stack-guard-gap-between-vmas.patch b/patches.fixes/mm-larger-stack-guard-gap-between-vmas.patch
new file mode 100644
index 0000000000..812c141cca
--- /dev/null
+++ b/patches.fixes/mm-larger-stack-guard-gap-between-vmas.patch
@@ -0,0 +1,859 @@
+From: Hugh Dickins <hughd@google.com>
+Subject: mm: larger stack guard gap, between vmas
+Git-commit: 1be7107fbe18eed3e319a6c3e83c78254b693acb
+Patch-mainline: 4.12-rc6
+References: bnc#1039348, CVE-2017-1000364, bnc#1045340
+
+mhocko@suse.com:
+backport taken from the stable tree
+
+commit 1be7107fbe18eed3e319a6c3e83c78254b693acb upstream.
+
+Stack guard page is a useful feature to reduce a risk of stack smashing
+into a different mapping. We have been using a single page gap which
+is sufficient to prevent having stack adjacent to a different mapping.
+But this seems to be insufficient in the light of the stack usage in
+userspace. E.g. glibc uses as large as 64kB alloca() in many commonly
+used functions. Others use constructs liks gid_t buffer[NGROUPS_MAX]
+which is 256kB or stack strings with MAX_ARG_STRLEN.
+
+This will become especially dangerous for suid binaries and the default
+no limit for the stack size limit because those applications can be
+tricked to consume a large portion of the stack and a single glibc call
+could jump over the guard page. These attacks are not theoretical,
+unfortunatelly.
+
+Make those attacks less probable by increasing the stack guard gap
+to 1MB (on systems with 4k pages; but make it depend on the page size
+because systems with larger base pages might cap stack allocations in
+the PAGE_SIZE units) which should cover larger alloca() and VLA stack
+allocations. It is obviously not a full fix because the problem is
+somehow inherent, but it should reduce attack space a lot.
+
+One could argue that the gap size should be configurable from userspace,
+but that can be done later when somebody finds that the new 1MB is wrong
+for some special case applications. For now, add a kernel command line
+option (stack_guard_gap) to specify the stack gap size (in page units).
+
+Implementation wise, first delete all the old code for stack guard page:
+because although we could get away with accounting one extra page in a
+stack vma, accounting a larger gap can break userspace - case in point,
+a program run with "ulimit -S -v 20000" failed when the 1MB gap was
+counted for RLIMIT_AS; similar problems could come with RLIMIT_MLOCK
+and strict non-overcommit mode.
+
+Instead of keeping gap inside the stack vma, maintain the stack guard
+gap as a gap between vmas: using vm_start_gap() in place of vm_start
+(or vm_end_gap() in place of vm_end if VM_GROWSUP) in just those few
+places which need to respect the gap - mainly arch_get_unmapped_area(),
+and and the vma tree's subtree_gap support for that.
+
+Original-patch-by: Oleg Nesterov <oleg@redhat.com>
+Original-patch-by: Michal Hocko <mhocko@suse.com>
+Signed-off-by: Hugh Dickins <hughd@google.com>
+Acked-by: Michal Hocko <mhocko@suse.com>
+Tested-by: Helge Deller <deller@gmx.de> # parisc
+Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
+[wt: backport to 4.11: adjust context]
+[wt: backport to 4.9: adjust context ; kernel doc was not in admin-guide]
+[wt: backport to 4.4: adjust context ; drop ppc hugetlb_radix changes]
+Signed-off-by: Willy Tarreau <w@1wt.eu>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+
+---
+ Documentation/kernel-parameters.txt | 7 +
+ arch/arc/mm/mmap.c | 2
+ arch/arm/mm/mmap.c | 4
+ arch/frv/mm/elf-fdpic.c | 2
+ arch/mips/mm/mmap.c | 2
+ arch/parisc/kernel/sys_parisc.c | 15 ++-
+ arch/powerpc/mm/slice.c | 2
+ arch/s390/mm/mmap.c | 4
+ arch/sh/mm/mmap.c | 4
+ arch/sparc/kernel/sys_sparc_64.c | 4
+ arch/sparc/mm/hugetlbpage.c | 2
+ arch/tile/mm/hugetlbpage.c | 2
+ arch/x86/kernel/sys_x86_64.c | 4
+ arch/x86/mm/hugetlbpage.c | 2
+ arch/xtensa/kernel/syscall.c | 2
+ fs/hugetlbfs/inode.c | 2
+ fs/proc/task_mmu.c | 4
+ include/linux/mm.h | 53 ++++++------
+ mm/gup.c | 5 -
+ mm/memory.c | 38 ---------
+ mm/mmap.c | 149 +++++++++++++++++++++---------------
+ 21 files changed, 149 insertions(+), 160 deletions(-)
+
+--- a/Documentation/kernel-parameters.txt
++++ b/Documentation/kernel-parameters.txt
+@@ -3620,6 +3620,13 @@ bytes respectively. Such letter suffixes
+ spia_pedr=
+ spia_peddr=
+
++ stack_guard_gap= [MM]
++ override the default stack gap protection. The value
++ is in page units and it defines how many pages prior
++ to (for stacks growing down) resp. after (for stacks
++ growing up) the main stack are reserved for no other
++ mapping. Default value is 256 pages.
++
+ stacktrace [FTRACE]
+ Enabled the stack tracer on boot up.
+
+--- a/arch/arc/mm/mmap.c
++++ b/arch/arc/mm/mmap.c
+@@ -64,7 +64,7 @@ arch_get_unmapped_area(struct file *filp
+
+ vma = find_vma(mm, addr);
+ if (TASK_SIZE - len >= addr &&
+- (!vma || addr + len <= vma->vm_start))
++ (!vma || addr + len <= vm_start_gap(vma)))
+ return addr;
+ }
+
+--- a/arch/arm/mm/mmap.c
++++ b/arch/arm/mm/mmap.c
+@@ -89,7 +89,7 @@ arch_get_unmapped_area(struct file *filp
+
+ vma = find_vma(mm, addr);
+ if (TASK_SIZE - len >= addr &&
+- (!vma || addr + len <= vma->vm_start))
++ (!vma || addr + len <= vm_start_gap(vma)))
+ return addr;
+ }
+
+@@ -140,7 +140,7 @@ arch_get_unmapped_area_topdown(struct fi
+ addr = PAGE_ALIGN(addr);
+ vma = find_vma(mm, addr);
+ if (TASK_SIZE - len >= addr &&
+- (!vma || addr + len <= vma->vm_start))
++ (!vma || addr + len <= vm_start_gap(vma)))
+ return addr;
+ }
+
+--- a/arch/frv/mm/elf-fdpic.c
++++ b/arch/frv/mm/elf-fdpic.c
+@@ -74,7 +74,7 @@ unsigned long arch_get_unmapped_area(str
+ addr = PAGE_ALIGN(addr);
+ vma = find_vma(current->mm, addr);
+ if (TASK_SIZE - len >= addr &&
+- (!vma || addr + len <= vma->vm_start))
++ (!vma || addr + len <= vm_start_gap(vma)))
+ goto success;
+ }
+
+--- a/arch/mips/mm/mmap.c
++++ b/arch/mips/mm/mmap.c
+@@ -92,7 +92,7 @@ static unsigned long arch_get_unmapped_a
+
+ vma = find_vma(mm, addr);
+ if (TASK_SIZE - len >= addr &&
+- (!vma || addr + len <= vma->vm_start))
++ (!vma || addr + len <= vm_start_gap(vma)))
+ return addr;
+ }
+
+--- a/arch/parisc/kernel/sys_parisc.c
++++ b/arch/parisc/kernel/sys_parisc.c
+@@ -88,7 +88,7 @@ unsigned long arch_get_unmapped_area(str
+ unsigned long len, unsigned long pgoff, unsigned long flags)
+ {
+ struct mm_struct *mm = current->mm;
+- struct vm_area_struct *vma;
++ struct vm_area_struct *vma, *prev;
+ unsigned long task_size = TASK_SIZE;
+ int do_color_align, last_mmap;
+ struct vm_unmapped_area_info info;
+@@ -115,9 +115,10 @@ unsigned long arch_get_unmapped_area(str
+ else
+ addr = PAGE_ALIGN(addr);
+
+- vma = find_vma(mm, addr);
++ vma = find_vma_prev(mm, addr, &prev);
+ if (task_size - len >= addr &&
+- (!vma || addr + len <= vma->vm_start))
++ (!vma || addr + len <= vm_start_gap(vma)) &&
++ (!prev || addr >= vm_end_gap(prev)))
+ goto found_addr;
+ }
+
+@@ -141,7 +142,7 @@ arch_get_unmapped_area_topdown(struct fi
+ const unsigned long len, const unsigned long pgoff,
+ const unsigned long flags)
+ {
+- struct vm_area_struct *vma;
++ struct vm_area_struct *vma, *prev;
+ struct mm_struct *mm = current->mm;
+ unsigned long addr = addr0;
+ int do_color_align, last_mmap;
+@@ -175,9 +176,11 @@ arch_get_unmapped_area_topdown(struct fi
+ addr = COLOR_ALIGN(addr, last_mmap, pgoff);
+ else
+ addr = PAGE_ALIGN(addr);
+- vma = find_vma(mm, addr);
++
++ vma = find_vma_prev(mm, addr, &prev);
+ if (TASK_SIZE - len >= addr &&
+- (!vma || addr + len <= vma->vm_start))
++ (!vma || addr + len <= vm_start_gap(vma)) &&
++ (!prev || addr >= vm_end_gap(prev)))
+ goto found_addr;
+ }
+
+--- a/arch/powerpc/mm/slice.c
++++ b/arch/powerpc/mm/slice.c
+@@ -105,7 +105,7 @@ static int slice_area_is_free(struct mm_
+ if ((mm->task_size - len) < addr)
+ return 0;
+ vma = find_vma(mm, addr);
+- return (!vma || (addr + len) <= vma->vm_start);
++ return (!vma || (addr + len) <= vm_start_gap(vma));
+ }
+
+ static int slice_low_has_vma(struct mm_struct *mm, unsigned long slice)
+--- a/arch/s390/mm/mmap.c
++++ b/arch/s390/mm/mmap.c
+@@ -97,7 +97,7 @@ arch_get_unmapped_area(struct file *filp
+ addr = PAGE_ALIGN(addr);
+ vma = find_vma(mm, addr);
+ if (TASK_SIZE - len >= addr && addr >= mmap_min_addr &&
+- (!vma || addr + len <= vma->vm_start))
++ (!vma || addr + len <= vm_start_gap(vma)))
+ return addr;
+ }
+
+@@ -135,7 +135,7 @@ arch_get_unmapped_area_topdown(struct fi
+ addr = PAGE_ALIGN(addr);
+ vma = find_vma(mm, addr);
+ if (TASK_SIZE - len >= addr && addr >= mmap_min_addr &&
+- (!vma || addr + len <= vma->vm_start))
++ (!vma || addr + len <= vm_start_gap(vma)))
+ return addr;
+ }
+
+--- a/arch/sh/mm/mmap.c
++++ b/arch/sh/mm/mmap.c
+@@ -63,7 +63,7 @@ unsigned long arch_get_unmapped_area(str
+
+ vma = find_vma(mm, addr);
+ if (TASK_SIZE - len >= addr &&
+- (!vma || addr + len <= vma->vm_start))
++ (!vma || addr + len <= vm_start_gap(vma)))
+ return addr;
+ }
+
+@@ -113,7 +113,7 @@ arch_get_unmapped_area_topdown(struct fi
+
+ vma = find_vma(mm, addr);
+ if (TASK_SIZE - len >= addr &&
+- (!vma || addr + len <= vma->vm_start))
++ (!vma || addr + len <= vm_start_gap(vma)))
+ return addr;
+ }
+
+--- a/arch/sparc/kernel/sys_sparc_64.c
++++ b/arch/sparc/kernel/sys_sparc_64.c
+@@ -118,7 +118,7 @@ unsigned long arch_get_unmapped_area(str
+
+ vma = find_vma(mm, addr);
+ if (task_size - len >= addr &&
+- (!vma || addr + len <= vma->vm_start))
++ (!vma || addr + len <= vm_start_gap(vma)))
+ return addr;
+ }
+
+@@ -181,7 +181,7 @@ arch_get_unmapped_area_topdown(struct fi
+
+ vma = find_vma(mm, addr);
+ if (task_size - len >= addr &&
+- (!vma || addr + len <= vma->vm_start))
++ (!vma || addr + len <= vm_start_gap(vma)))
+ return addr;
+ }
+
+--- a/arch/sparc/mm/hugetlbpage.c
++++ b/arch/sparc/mm/hugetlbpage.c
+@@ -115,7 +115,7 @@ hugetlb_get_unmapped_area(struct file *f
+ addr = ALIGN(addr, HPAGE_SIZE);
+ vma = find_vma(mm, addr);
+ if (task_size - len >= addr &&
+- (!vma || addr + len <= vma->vm_start))
++ (!vma || addr + len <= vm_start_gap(vma)))
+ return addr;
+ }
+ if (mm->get_unmapped_area == arch_get_unmapped_area)
+--- a/arch/tile/mm/hugetlbpage.c
++++ b/arch/tile/mm/hugetlbpage.c
+@@ -232,7 +232,7 @@ unsigned long hugetlb_get_unmapped_area(
+ addr = ALIGN(addr, huge_page_size(h));
+ vma = find_vma(mm, addr);
+ if (TASK_SIZE - len >= addr &&
+- (!vma || addr + len <= vma->vm_start))
++ (!vma || addr + len <= vm_start_gap(vma)))
+ return addr;
+ }
+ if (current->mm->get_unmapped_area == arch_get_unmapped_area)
+--- a/arch/x86/kernel/sys_x86_64.c
++++ b/arch/x86/kernel/sys_x86_64.c
+@@ -143,7 +143,7 @@ arch_get_unmapped_area(struct file *filp
+ addr = PAGE_ALIGN(addr);
+ vma = find_vma(mm, addr);
+ if (end - len >= addr &&
+- (!vma || addr + len <= vma->vm_start))
++ (!vma || addr + len <= vm_start_gap(vma)))
+ return addr;
+ }
+
+@@ -186,7 +186,7 @@ arch_get_unmapped_area_topdown(struct fi
+ addr = PAGE_ALIGN(addr);
+ vma = find_vma(mm, addr);
+ if (TASK_SIZE - len >= addr &&
+- (!vma || addr + len <= vma->vm_start))
++ (!vma || addr + len <= vm_start_gap(vma)))
+ return addr;
+ }
+
+--- a/arch/x86/mm/hugetlbpage.c
++++ b/arch/x86/mm/hugetlbpage.c
+@@ -144,7 +144,7 @@ hugetlb_get_unmapped_area(struct file *f
+ addr = ALIGN(addr, huge_page_size(h));
+ vma = find_vma(mm, addr);
+ if (TASK_SIZE - len >= addr &&
+- (!vma || addr + len <= vma->vm_start))
++ (!vma || addr + len <= vm_start_gap(vma)))
+ return addr;
+ }
+ if (mm->get_unmapped_area == arch_get_unmapped_area)
+--- a/arch/xtensa/kernel/syscall.c
++++ b/arch/xtensa/kernel/syscall.c
+@@ -87,7 +87,7 @@ unsigned long arch_get_unmapped_area(str
+ /* At this point: (!vmm || addr < vmm->vm_end). */
+ if (TASK_SIZE - len < addr)
+ return -ENOMEM;
+- if (!vmm || addr + len <= vmm->vm_start)
++ if (!vmm || addr + len <= vm_start_gap(vmm))
+ return addr;
+ addr = vmm->vm_end;
+ if (flags & MAP_SHARED)
+--- a/fs/hugetlbfs/inode.c
++++ b/fs/hugetlbfs/inode.c
+@@ -191,7 +191,7 @@ hugetlb_get_unmapped_area(struct file *f
+ addr = ALIGN(addr, huge_page_size(h));
+ vma = find_vma(mm, addr);
+ if (TASK_SIZE - len >= addr &&
+- (!vma || addr + len <= vma->vm_start))
++ (!vma || addr + len <= vm_start_gap(vma)))
+ return addr;
+ }
+
+--- a/fs/proc/task_mmu.c
++++ b/fs/proc/task_mmu.c
+@@ -307,11 +307,7 @@ show_map_vma(struct seq_file *m, struct
+
+ /* We don't show the stack guard page in /proc/maps */
+ start = vma->vm_start;
+- if (stack_guard_page_start(vma, start))
+- start += PAGE_SIZE;
+ end = vma->vm_end;
+- if (stack_guard_page_end(vma, end))
+- end -= PAGE_SIZE;
+
+ seq_setwidth(m, 25 + sizeof(void *) * 6 - 1);
+ seq_printf(m, "%08lx-%08lx %c%c%c%c %08llx %02x:%02x %lu ",
+--- a/include/linux/mm.h
++++ b/include/linux/mm.h
+@@ -1280,39 +1280,11 @@ int clear_page_dirty_for_io(struct page
+
+ int get_cmdline(struct task_struct *task, char *buffer, int buflen);
+
+-/* Is the vma a continuation of the stack vma above it? */
+-static inline int vma_growsdown(struct vm_area_struct *vma, unsigned long addr)
+-{
+- return vma && (vma->vm_end == addr) && (vma->vm_flags & VM_GROWSDOWN);
+-}
+-
+ static inline bool vma_is_anonymous(struct vm_area_struct *vma)
+ {
+ return !vma->vm_ops;
+ }
+
+-static inline int stack_guard_page_start(struct vm_area_struct *vma,
+- unsigned long addr)
+-{
+- return (vma->vm_flags & VM_GROWSDOWN) &&
+- (vma->vm_start == addr) &&
+- !vma_growsdown(vma->vm_prev, addr);
+-}
+-
+-/* Is the vma a continuation of the stack vma below it? */
+-static inline int vma_growsup(struct vm_area_struct *vma, unsigned long addr)
+-{
+- return vma && (vma->vm_start == addr) && (vma->vm_flags & VM_GROWSUP);
+-}
+-
+-static inline int stack_guard_page_end(struct vm_area_struct *vma,
+- unsigned long addr)
+-{
+- return (vma->vm_flags & VM_GROWSUP) &&
+- (vma->vm_end == addr) &&
+- !vma_growsup(vma->vm_next, addr);
+-}
+-
+ int vma_is_stack_for_task(struct vm_area_struct *vma, struct task_struct *t);
+
+ extern unsigned long move_page_tables(struct vm_area_struct *vma,
+@@ -2034,6 +2006,7 @@ void page_cache_async_readahead(struct a
+ pgoff_t offset,
+ unsigned long size);
+
++extern unsigned long stack_guard_gap;
+ /* Generic expand stack which grows the stack according to GROWS{UP,DOWN} */
+ extern int expand_stack(struct vm_area_struct *vma, unsigned long address);
+
+@@ -2062,6 +2035,30 @@ static inline struct vm_area_struct * fi
+ return vma;
+ }
+
++static inline unsigned long vm_start_gap(struct vm_area_struct *vma)
++{
++ unsigned long vm_start = vma->vm_start;
++
++ if (vma->vm_flags & VM_GROWSDOWN) {
++ vm_start -= stack_guard_gap;
++ if (vm_start > vma->vm_start)
++ vm_start = 0;
++ }
++ return vm_start;
++}
++
++static inline unsigned long vm_end_gap(struct vm_area_struct *vma)
++{
++ unsigned long vm_end = vma->vm_end;
++
++ if (vma->vm_flags & VM_GROWSUP) {
++ vm_end += stack_guard_gap;
++ if (vm_end < vma->vm_end)
++ vm_end = -PAGE_SIZE;
++ }
++ return vm_end;
++}
++
+ static inline unsigned long vma_pages(struct vm_area_struct *vma)
+ {
+ return (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
+--- a/mm/gup.c
++++ b/mm/gup.c
+@@ -312,11 +312,6 @@ static int faultin_page(struct task_stru
+ /* mlock all present pages, but do not fault in new pages */
+ if ((*flags & (FOLL_POPULATE | FOLL_MLOCK)) == FOLL_MLOCK)
+ return -ENOENT;
+- /* For mm_populate(), just skip the stack guard page. */
+- if ((*flags & FOLL_POPULATE) &&
+- (stack_guard_page_start(vma, address) ||
+- stack_guard_page_end(vma, address + PAGE_SIZE)))
+- return -ENOENT;
+ if (*flags & FOLL_WRITE)
+ fault_flags |= FAULT_FLAG_WRITE;
+ if (nonblocking)
+--- a/mm/memory.c
++++ b/mm/memory.c
+@@ -2667,40 +2667,6 @@ out_release:
+ }
+
+ /*
+- * This is like a special single-page "expand_{down|up}wards()",
+- * except we must first make sure that 'address{-|+}PAGE_SIZE'
+- * doesn't hit another vma.
+- */
+-static inline int check_stack_guard_page(struct vm_area_struct *vma, unsigned long address)
+-{
+- address &= PAGE_MASK;
+- if ((vma->vm_flags & VM_GROWSDOWN) && address == vma->vm_start) {
+- struct vm_area_struct *prev = vma->vm_prev;
+-
+- /*
+- * Is there a mapping abutting this one below?
+- *
+- * That's only ok if it's the same stack mapping
+- * that has gotten split..
+- */
+- if (prev && prev->vm_end == address)
+- return prev->vm_flags & VM_GROWSDOWN ? 0 : -ENOMEM;
+-
+- return expand_downwards(vma, address - PAGE_SIZE);
+- }
+- if ((vma->vm_flags & VM_GROWSUP) && address + PAGE_SIZE == vma->vm_end) {
+- struct vm_area_struct *next = vma->vm_next;
+-
+- /* As VM_GROWSDOWN but s/below/above/ */
+- if (next && next->vm_start == address + PAGE_SIZE)
+- return next->vm_flags & VM_GROWSUP ? 0 : -ENOMEM;
+-
+- return expand_upwards(vma, address + PAGE_SIZE);
+- }
+- return 0;
+-}
+-
+-/*
+ * We enter with non-exclusive mmap_sem (to exclude vma changes,
+ * but allow concurrent faults), and pte mapped but not yet locked.
+ * We return with mmap_sem still held, but pte unmapped and unlocked.
+@@ -2720,10 +2686,6 @@ static int do_anonymous_page(struct mm_s
+ if (vma->vm_flags & VM_SHARED)
+ return VM_FAULT_SIGBUS;
+
+- /* Check if we need to add a guard page to the stack */
+- if (check_stack_guard_page(vma, address) < 0)
+- return VM_FAULT_SIGSEGV;
+-
+ /* Use the zero-page for reads */
+ if (!(flags & FAULT_FLAG_WRITE) && !mm_forbids_zeropage(mm)) {
+ entry = pte_mkspecial(pfn_pte(my_zero_pfn(address),
+--- a/mm/mmap.c
++++ b/mm/mmap.c
+@@ -288,6 +288,7 @@ SYSCALL_DEFINE1(brk, unsigned long, brk)
+ unsigned long retval;
+ unsigned long newbrk, oldbrk;
+ struct mm_struct *mm = current->mm;
++ struct vm_area_struct *next;
+ unsigned long min_brk;
+ bool populate;
+
+@@ -332,7 +333,8 @@ SYSCALL_DEFINE1(brk, unsigned long, brk)
+ }
+
+ /* Check against existing mmap mappings. */
+- if (find_vma_intersection(mm, oldbrk, newbrk+PAGE_SIZE))
++ next = find_vma(mm, oldbrk);
++ if (next && newbrk + PAGE_SIZE > vm_start_gap(next))
+ goto out;
+
+ /* Ok, looks good - let it rip. */
+@@ -355,10 +357,22 @@ out:
+
+ static long vma_compute_subtree_gap(struct vm_area_struct *vma)
+ {
+- unsigned long max, subtree_gap;
+- max = vma->vm_start;
+- if (vma->vm_prev)
+- max -= vma->vm_prev->vm_end;
++ unsigned long max, prev_end, subtree_gap;
++
++ /*
++ * Note: in the rare case of a VM_GROWSDOWN above a VM_GROWSUP, we
++ * allow two stack_guard_gaps between them here, and when choosing
++ * an unmapped area; whereas when expanding we only require one.
++ * That's a little inconsistent, but keeps the code here simpler.
++ */
++ max = vm_start_gap(vma);
++ if (vma->vm_prev) {
++ prev_end = vm_end_gap(vma->vm_prev);
++ if (max > prev_end)
++ max -= prev_end;
++ else
++ max = 0;
++ }
+ if (vma->vm_rb.rb_left) {
+ subtree_gap = rb_entry(vma->vm_rb.rb_left,
+ struct vm_area_struct, vm_rb)->rb_subtree_gap;
+@@ -451,7 +465,7 @@ static void validate_mm(struct mm_struct
+ anon_vma_unlock_read(anon_vma);
+ }
+
+- highest_address = vma->vm_end;
++ highest_address = vm_end_gap(vma);
+ vma = vma->vm_next;
+ i++;
+ }
+@@ -620,7 +634,7 @@ void __vma_link_rb(struct mm_struct *mm,
+ if (vma->vm_next)
+ vma_gap_update(vma->vm_next);
+ else
+- mm->highest_vm_end = vma->vm_end;
++ mm->highest_vm_end = vm_end_gap(vma);
+
+ /*
+ * vma->vm_prev wasn't known when we followed the rbtree to find the
+@@ -866,7 +880,7 @@ again: remove_next = 1 + (end > next->
+ vma_gap_update(vma);
+ if (end_changed) {
+ if (!next)
+- mm->highest_vm_end = end;
++ mm->highest_vm_end = vm_end_gap(vma);
+ else if (!adjust_next)
+ vma_gap_update(next);
+ }
+@@ -909,7 +923,7 @@ again: remove_next = 1 + (end > next->
+ else if (next)
+ vma_gap_update(next);
+ else
+- mm->highest_vm_end = end;
++ VM_WARN_ON(mm->highest_vm_end != vm_end_gap(vma));
+ }
+ if (insert && file)
+ uprobe_mmap(insert);
+@@ -1741,7 +1755,7 @@ unsigned long unmapped_area(struct vm_un
+
+ while (true) {
+ /* Visit left subtree if it looks promising */
+- gap_end = vma->vm_start;
++ gap_end = vm_start_gap(vma);
+ if (gap_end >= low_limit && vma->vm_rb.rb_left) {
+ struct vm_area_struct *left =
+ rb_entry(vma->vm_rb.rb_left,
+@@ -1752,7 +1766,7 @@ unsigned long unmapped_area(struct vm_un
+ }
+ }
+
+- gap_start = vma->vm_prev ? vma->vm_prev->vm_end : 0;
++ gap_start = vma->vm_prev ? vm_end_gap(vma->vm_prev) : 0;
+ check_current:
+ /* Check if current node has a suitable gap */
+ if (gap_start > high_limit)
+@@ -1779,8 +1793,8 @@ check_current:
+ vma = rb_entry(rb_parent(prev),
+ struct vm_area_struct, vm_rb);
+ if (prev == vma->vm_rb.rb_left) {
+- gap_start = vma->vm_prev->vm_end;
+- gap_end = vma->vm_start;
++ gap_start = vm_end_gap(vma->vm_prev);
++ gap_end = vm_start_gap(vma);
+ goto check_current;
+ }
+ }
+@@ -1844,7 +1858,7 @@ unsigned long unmapped_area_topdown(stru
+
+ while (true) {
+ /* Visit right subtree if it looks promising */
+- gap_start = vma->vm_prev ? vma->vm_prev->vm_end : 0;
++ gap_start = vma->vm_prev ? vm_end_gap(vma->vm_prev) : 0;
+ if (gap_start <= high_limit && vma->vm_rb.rb_right) {
+ struct vm_area_struct *right =
+ rb_entry(vma->vm_rb.rb_right,
+@@ -1857,7 +1871,7 @@ unsigned long unmapped_area_topdown(stru
+
+ check_current:
+ /* Check if current node has a suitable gap */
+- gap_end = vma->vm_start;
++ gap_end = vm_start_gap(vma);
+ if (gap_end < low_limit)
+ return -ENOMEM;
+ if (gap_start <= high_limit && gap_end - gap_start >= length)
+@@ -1883,7 +1897,7 @@ check_current:
+ struct vm_area_struct, vm_rb);
+ if (prev == vma->vm_rb.rb_right) {
+ gap_start = vma->vm_prev ?
+- vma->vm_prev->vm_end : 0;
++ vm_end_gap(vma->vm_prev) : 0;
+ goto check_current;
+ }
+ }
+@@ -1921,7 +1935,7 @@ arch_get_unmapped_area(struct file *filp
+ unsigned long len, unsigned long pgoff, unsigned long flags)
+ {
+ struct mm_struct *mm = current->mm;
+- struct vm_area_struct *vma;
++ struct vm_area_struct *vma, *prev;
+ struct vm_unmapped_area_info info;
+
+ if (len > TASK_SIZE - mmap_min_addr)
+@@ -1932,9 +1946,10 @@ arch_get_unmapped_area(struct file *filp
+
+ if (addr) {
+ addr = PAGE_ALIGN(addr);
+- vma = find_vma(mm, addr);
++ vma = find_vma_prev(mm, addr, &prev);
+ if (TASK_SIZE - len >= addr && addr >= mmap_min_addr &&
+- (!vma || addr + len <= vma->vm_start))
++ (!vma || addr + len <= vm_start_gap(vma)) &&
++ (!prev || addr >= vm_end_gap(prev)))
+ return addr;
+ }
+
+@@ -1957,7 +1972,7 @@ arch_get_unmapped_area_topdown(struct fi
+ const unsigned long len, const unsigned long pgoff,
+ const unsigned long flags)
+ {
+- struct vm_area_struct *vma;
++ struct vm_area_struct *vma, *prev;
+ struct mm_struct *mm = current->mm;
+ unsigned long addr = addr0;
+ struct vm_unmapped_area_info info;
+@@ -1972,9 +1987,10 @@ arch_get_unmapped_area_topdown(struct fi
+ /* requesting a specific address */
+ if (addr) {
+ addr = PAGE_ALIGN(addr);
+- vma = find_vma(mm, addr);
++ vma = find_vma_prev(mm, addr, &prev);
+ if (TASK_SIZE - len >= addr && addr >= mmap_min_addr &&
+- (!vma || addr + len <= vma->vm_start))
++ (!vma || addr + len <= vm_start_gap(vma)) &&
++ (!prev || addr >= vm_end_gap(prev)))
+ return addr;
+ }
+
+@@ -2099,21 +2115,19 @@ find_vma_prev(struct mm_struct *mm, unsi
+ * update accounting. This is shared with both the
+ * grow-up and grow-down cases.
+ */
+-static int acct_stack_growth(struct vm_area_struct *vma, unsigned long size, unsigned long grow)
++static int acct_stack_growth(struct vm_area_struct *vma,
++ unsigned long size, unsigned long grow)
+ {
+ struct mm_struct *mm = vma->vm_mm;
+ struct rlimit *rlim = current->signal->rlim;
+- unsigned long new_start, actual_size;
++ unsigned long new_start;
+
+ /* address space limit tests */
+ if (!may_expand_vm(mm, grow))
+ return -ENOMEM;
+
+ /* Stack limit test */
+- actual_size = size;
+- if (size && (vma->vm_flags & (VM_GROWSUP | VM_GROWSDOWN)))
+- actual_size -= PAGE_SIZE;
+- if (actual_size > READ_ONCE(rlim[RLIMIT_STACK].rlim_cur))
++ if (size > READ_ONCE(rlim[RLIMIT_STACK].rlim_cur))
+ return -ENOMEM;
+
+ /* mlock limit tests */
+@@ -2151,17 +2165,30 @@ static int acct_stack_growth(struct vm_a
+ int expand_upwards(struct vm_area_struct *vma, unsigned long address)
+ {
+ struct mm_struct *mm = vma->vm_mm;
++ struct vm_area_struct *next;
++ unsigned long gap_addr;
+ int error = 0;
+
+ if (!(vma->vm_flags & VM_GROWSUP))
+ return -EFAULT;
+
+ /* Guard against wrapping around to address 0. */
+- if (address < PAGE_ALIGN(address+4))
+- address = PAGE_ALIGN(address+4);
+- else
++ address &= PAGE_MASK;
++ address += PAGE_SIZE;
++ if (!address)
+ return -ENOMEM;
+
++ /* Enforce stack_guard_gap */
++ gap_addr = address + stack_guard_gap;
++ if (gap_addr < address)
++ return -ENOMEM;
++ next = vma->vm_next;
++ if (next && next->vm_start < gap_addr) {
++ if (!(next->vm_flags & VM_GROWSUP))
++ return -ENOMEM;
++ /* Check that both stack segments have the same anon_vma? */
++ }
++
+ /* We must make sure the anon_vma is allocated. */
+ if (unlikely(anon_vma_prepare(vma)))
+ return -ENOMEM;
+@@ -2206,7 +2233,7 @@ int expand_upwards(struct vm_area_struct
+ if (vma->vm_next)
+ vma_gap_update(vma->vm_next);
+ else
+- mm->highest_vm_end = address;
++ mm->highest_vm_end = vm_end_gap(vma);
+ spin_unlock(&mm->page_table_lock);
+
+ perf_event_mmap(vma);
+@@ -2227,6 +2254,8 @@ int expand_downwards(struct vm_area_stru
+ unsigned long address)
+ {
+ struct mm_struct *mm = vma->vm_mm;
++ struct vm_area_struct *prev;
++ unsigned long gap_addr;
+ int error;
+
+ address &= PAGE_MASK;
+@@ -2234,6 +2263,17 @@ int expand_downwards(struct vm_area_stru
+ if (error)
+ return error;
+
++ /* Enforce stack_guard_gap */
++ gap_addr = address - stack_guard_gap;
++ if (gap_addr > address)
++ return -ENOMEM;
++ prev = vma->vm_prev;
++ if (prev && prev->vm_end > gap_addr) {
++ if (!(prev->vm_flags & VM_GROWSDOWN))
++ return -ENOMEM;
++ /* Check that both stack segments have the same anon_vma? */
++ }
++
+ /* We must make sure the anon_vma is allocated. */
+ if (unlikely(anon_vma_prepare(vma)))
+ return -ENOMEM;
+@@ -2289,28 +2329,25 @@ int expand_downwards(struct vm_area_stru
+ return error;
+ }
+
+-/*
+- * Note how expand_stack() refuses to expand the stack all the way to
+- * abut the next virtual mapping, *unless* that mapping itself is also
+- * a stack mapping. We want to leave room for a guard page, after all
+- * (the guard page itself is not added here, that is done by the
+- * actual page faulting logic)
+- *
+- * This matches the behavior of the guard page logic (see mm/memory.c:
+- * check_stack_guard_page()), which only allows the guard page to be
+- * removed under these circumstances.
+- */
++/* enforced gap between the expanding stack and other mappings. */
++unsigned long stack_guard_gap = 256UL<<PAGE_SHIFT;
++
++static int __init cmdline_parse_stack_guard_gap(char *p)
++{
++ unsigned long val;
++ char *endptr;
++
++ val = simple_strtoul(p, &endptr, 10);
++ if (!*endptr)
++ stack_guard_gap = val << PAGE_SHIFT;
++
++ return 0;
++}
++__setup("stack_guard_gap=", cmdline_parse_stack_guard_gap);
++
+ #ifdef CONFIG_STACK_GROWSUP
+ int expand_stack(struct vm_area_struct *vma, unsigned long address)
+ {
+- struct vm_area_struct *next;
+-
+- address &= PAGE_MASK;
+- next = vma->vm_next;
+- if (next && next->vm_start == address + PAGE_SIZE) {
+- if (!(next->vm_flags & VM_GROWSUP))
+- return -ENOMEM;
+- }
+ return expand_upwards(vma, address);
+ }
+
+@@ -2332,14 +2369,6 @@ find_extend_vma(struct mm_struct *mm, un
+ #else
+ int expand_stack(struct vm_area_struct *vma, unsigned long address)
+ {
+- struct vm_area_struct *prev;
+-
+- address &= PAGE_MASK;
+- prev = vma->vm_prev;
+- if (prev && prev->vm_end == address) {
+- if (!(prev->vm_flags & VM_GROWSDOWN))
+- return -ENOMEM;
+- }
+ return expand_downwards(vma, address);
+ }
+
+@@ -2437,7 +2466,7 @@ detach_vmas_to_be_unmapped(struct mm_str
+ vma->vm_prev = prev;
+ vma_gap_update(vma);
+ } else
+- mm->highest_vm_end = prev ? prev->vm_end : 0;
++ mm->highest_vm_end = prev ? vm_end_gap(prev) : 0;
+ tail_vma->vm_next = NULL;
+
+ /* Kill the cache */
diff --git a/series.conf b/series.conf
index 14ec9c1043..c8441feb34 100644
--- a/series.conf
+++ b/series.conf
@@ -1735,8 +1735,9 @@
patches.fixes/mm-page_alloc-skip-over-regions-of-invalid-pfns-wher.patch
patches.fixes/mm-memblock.c-fix-memblock_next_valid_pfn.patch
- patches.fixes/0001-mm-enlarge-stack-guard-gap.patch
- patches.fixes/0002-mm-do-not-collapse-stack-gap-into-THP.patch
+ # CVE-2017-1000364
+ patches.fixes/mm-larger-stack-guard-gap-between-vmas.patch
+ patches.fixes/mm-fix-new-crash-in-unmapped_area_topdown.patch
########################################################
# IPC patches