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authorJann Horn <jannh@google.com>2017-11-14 01:03:44 +0100
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2017-11-24 08:32:25 +0100
commita3805b10de80953db316985f567453fc18329423 (patch)
parent3630b28019075639a9db00491349e05fbf0f901e (diff)
mm/pagewalk.c: report holes in hugetlb ranges
commit 373c4557d2aa362702c4c2d41288fb1e54990b7c upstream. This matters at least for the mincore syscall, which will otherwise copy uninitialized memory from the page allocator to userspace. It is probably also a correctness error for /proc/$pid/pagemap, but I haven't tested that. Removing the `walk->hugetlb_entry` condition in walk_hugetlb_range() has no effect because the caller already checks for that. This only reports holes in hugetlb ranges to callers who have specified a hugetlb_entry callback. This issue was found using an AFL-based fuzzer. v2: - don't crash on ->pte_hole==NULL (Andrew Morton) - add Cc stable (Andrew Morton) Changed for 4.4/4.9 stable backport: - fix up conflict in the huge_pte_offset() call Fixes: 1e25a271c8ac ("mincore: apply page table walker on do_mincore()") Signed-off-by: Jann Horn <jannh@google.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
1 files changed, 5 insertions, 1 deletions
diff --git a/mm/pagewalk.c b/mm/pagewalk.c
index 29f2f8b853ae..c2cbd2620169 100644
--- a/mm/pagewalk.c
+++ b/mm/pagewalk.c
@@ -142,8 +142,12 @@ static int walk_hugetlb_range(unsigned long addr, unsigned long end,
do {
next = hugetlb_entry_end(h, addr, end);
pte = huge_pte_offset(walk->mm, addr & hmask);
- if (pte && walk->hugetlb_entry)
+ if (pte)
err = walk->hugetlb_entry(pte, hmask, addr, next, walk);
+ else if (walk->pte_hole)
+ err = walk->pte_hole(addr, next, walk);
if (err)
} while (addr = next, addr != end);