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authorJarod Wilson <jwilson@redhat.com>2008-09-09 12:38:56 +0200
committerGreg Kroah-Hartman <gregkh@suse.de>2008-10-08 20:23:12 -0700
commit34f3c11bc4d09fe7d3b105b5e4e6127dc4d8ee24 (patch)
treeed8d9a518a7bdc58930541826bcab0244260eae4
parent553d7dd7336a3c1f3dd12085b5c42451c17225e1 (diff)
S390: CVE-2008-1514: prevent ptrace padding area read/write in 31-bit mode
commit 3d6e48f43340343d97839eadb1ab7b6a3ea98797 upstream When running a 31-bit ptrace, on either an s390 or s390x kernel, reads and writes into a padding area in struct user_regs_struct32 will result in a kernel panic. This is also known as CVE-2008-1514. Test case available here: http://sources.redhat.com/cgi-bin/cvsweb.cgi/~checkout~/tests/ptrace-tests/tests/user-area-padding.c?cvsroot=systemtap Steps to reproduce: 1) wget the above 2) gcc -o user-area-padding-31bit user-area-padding.c -Wall -ggdb2 -D_GNU_SOURCE -m31 3) ./user-area-padding-31bit <panic> Test status ----------- Without patch, both s390 and s390x kernels panic. With patch, the test case, as well as the gdb testsuite, pass without incident, padding area reads returning zero, writes ignored. Nb: original version returned -EINVAL on write attempts, which broke the gdb test and made the test case slightly unhappy, Jan Kratochvil suggested the change to return 0 on write attempts. Signed-off-by: Jarod Wilson <jarod@redhat.com> Tested-by: Jan Kratochvil <jan.kratochvil@redhat.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Moritz Muehlenhoff <jmm@debian.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
-rw-r--r--arch/s390/kernel/compat_ptrace.h1
-rw-r--r--arch/s390/kernel/ptrace.c28
2 files changed, 29 insertions, 0 deletions
diff --git a/arch/s390/kernel/compat_ptrace.h b/arch/s390/kernel/compat_ptrace.h
index 419aef913ee1..7731b8216f9a 100644
--- a/arch/s390/kernel/compat_ptrace.h
+++ b/arch/s390/kernel/compat_ptrace.h
@@ -42,6 +42,7 @@ struct user_regs_struct32
u32 gprs[NUM_GPRS];
u32 acrs[NUM_ACRS];
u32 orig_gpr2;
+ /* nb: there's a 4-byte hole here */
s390_fp_regs fp_regs;
/*
* These per registers are in here so that gdb can modify them
diff --git a/arch/s390/kernel/ptrace.c b/arch/s390/kernel/ptrace.c
index 35827b9bd4d1..75fea19ce752 100644
--- a/arch/s390/kernel/ptrace.c
+++ b/arch/s390/kernel/ptrace.c
@@ -177,6 +177,13 @@ peek_user(struct task_struct *child, addr_t addr, addr_t data)
*/
tmp = (addr_t) task_pt_regs(child)->orig_gpr2;
+ } else if (addr < (addr_t) &dummy->regs.fp_regs) {
+ /*
+ * prevent reads of padding hole between
+ * orig_gpr2 and fp_regs on s390.
+ */
+ tmp = 0;
+
} else if (addr < (addr_t) (&dummy->regs.fp_regs + 1)) {
/*
* floating point regs. are stored in the thread structure
@@ -268,6 +275,13 @@ poke_user(struct task_struct *child, addr_t addr, addr_t data)
*/
task_pt_regs(child)->orig_gpr2 = data;
+ } else if (addr < (addr_t) &dummy->regs.fp_regs) {
+ /*
+ * prevent writes of padding hole between
+ * orig_gpr2 and fp_regs on s390.
+ */
+ return 0;
+
} else if (addr < (addr_t) (&dummy->regs.fp_regs + 1)) {
/*
* floating point regs. are stored in the thread structure
@@ -409,6 +423,13 @@ peek_user_emu31(struct task_struct *child, addr_t addr, addr_t data)
*/
tmp = *(__u32*)((addr_t) &task_pt_regs(child)->orig_gpr2 + 4);
+ } else if (addr < (addr_t) &dummy32->regs.fp_regs) {
+ /*
+ * prevent reads of padding hole between
+ * orig_gpr2 and fp_regs on s390.
+ */
+ tmp = 0;
+
} else if (addr < (addr_t) (&dummy32->regs.fp_regs + 1)) {
/*
* floating point regs. are stored in the thread structure
@@ -488,6 +509,13 @@ poke_user_emu31(struct task_struct *child, addr_t addr, addr_t data)
*/
*(__u32*)((addr_t) &task_pt_regs(child)->orig_gpr2 + 4) = tmp;
+ } else if (addr < (addr_t) &dummy32->regs.fp_regs) {
+ /*
+ * prevent writess of padding hole between
+ * orig_gpr2 and fp_regs on s390.
+ */
+ return 0;
+
} else if (addr < (addr_t) (&dummy32->regs.fp_regs + 1)) {
/*
* floating point regs. are stored in the thread structure