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authorJohn Wright <john.wright@hp.com>2009-04-29 14:32:01 -0600
committerIngo Molnar <mingo@elte.hu>2009-04-30 12:31:45 +0200
commit2f65dd475c6a8a997145ea83cc3d2d5e6dc55af1 (patch)
treeea094eebb66277be8f5d67884f3dd55a609d1bc4 /arch/x86/vdso
parent091438dd5668396328a3419abcbc6591159eb8d1 (diff)
x86: gettimeofday() vDSO: fix segfault when tv == NULL
According to the gettimeofday(2) manual: If either tv or tz is NULL, the corresponding structure is not set or returned. Since it is legal to give NULL as the tv argument, the code should make sure tv is not NULL before trying to dereference it. This issue manifests itself on x86_64 when vdso=0 is not on the kernel command-line and libc uses the vDSO for gettimeofday() (e.g. glibc >= 2.7). A simple reproducer: #include <stdio.h> #include <sys/time.h> int main(void) { struct timezone tz; gettimeofday(NULL, &tz); return 0; } See http://bugs.debian.org/466491 for more details. [ Impact: fix gettimeofday(NULL, &tz) segfault ] Signed-off-by: John Wright <john.wright@hp.com> Cc: Andi Kleen <ak@suse.de> Cc: John Wright <john.wright@hp.com> LKML-Reference: <1241037121-14805-1-git-send-email-john.wright@hp.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'arch/x86/vdso')
-rw-r--r--arch/x86/vdso/vclock_gettime.c12
1 files changed, 7 insertions, 5 deletions
diff --git a/arch/x86/vdso/vclock_gettime.c b/arch/x86/vdso/vclock_gettime.c
index d9d35824c56..6a40b78b46a 100644
--- a/arch/x86/vdso/vclock_gettime.c
+++ b/arch/x86/vdso/vclock_gettime.c
@@ -104,11 +104,13 @@ notrace int __vdso_gettimeofday(struct timeval *tv, struct timezone *tz)
{
long ret;
if (likely(gtod->sysctl_enabled && gtod->clock.vread)) {
- BUILD_BUG_ON(offsetof(struct timeval, tv_usec) !=
- offsetof(struct timespec, tv_nsec) ||
- sizeof(*tv) != sizeof(struct timespec));
- do_realtime((struct timespec *)tv);
- tv->tv_usec /= 1000;
+ if (likely(tv != NULL)) {
+ BUILD_BUG_ON(offsetof(struct timeval, tv_usec) !=
+ offsetof(struct timespec, tv_nsec) ||
+ sizeof(*tv) != sizeof(struct timespec));
+ do_realtime((struct timespec *)tv);
+ tv->tv_usec /= 1000;
+ }
if (unlikely(tz != NULL)) {
/* Avoid memcpy. Some old compilers fail to inline it */
tz->tz_minuteswest = gtod->sys_tz.tz_minuteswest;