diff options
| author | Jarod Wilson <jwilson@redhat.com> | 2008-09-09 12:38:56 +0200 |
|---|---|---|
| committer | Martin Schwidefsky <schwidefsky@de.ibm.com> | 2008-09-09 12:39:06 +0200 |
| commit | 3d6e48f43340343d97839eadb1ab7b6a3ea98797 (patch) | |
| tree | 81d1c8709ef5a1dc8cd8c6e44072928f7c0f903a | |
| parent | 82a28c794f27aac17d7a3ebd7f14d731a11a5532 (diff) | |
[S390] CVE-2008-1514: prevent ptrace padding area read/write in 31-bit mode
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>
| -rw-r--r-- | arch/s390/kernel/compat_ptrace.h | 1 | ||||
| -rw-r--r-- | arch/s390/kernel/ptrace.c | 28 |
2 files changed, 29 insertions, 0 deletions
diff --git a/arch/s390/kernel/compat_ptrace.h b/arch/s390/kernel/compat_ptrace.h index cde81fa64f8..a2be3a978d5 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 2815bfe348a..c8b08289eb8 100644 --- a/arch/s390/kernel/ptrace.c +++ b/arch/s390/kernel/ptrace.c @@ -170,6 +170,13 @@ static unsigned long __peek_user(struct task_struct *child, addr_t addr) */ 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 @@ -270,6 +277,13 @@ static int __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 @@ -428,6 +442,13 @@ static u32 __peek_user_compat(struct task_struct *child, addr_t addr) */ 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 @@ -514,6 +535,13 @@ static int __poke_user_compat(struct task_struct *child, */ *(__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 |