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authorJohn Stultz <john.stultz@linaro.org>2012-08-08 23:36:20 +0400
committerThomas Gleixner <tglx@linutronix.de>2012-08-15 17:54:01 +0400
commit4e8b14526ca7fb046a81c94002c1c43b6fdf0e9b (patch)
treed0681e8e99fe2fbae1bfa574a8a68320ae5c7c1f /include/linux/time.h
parent3bf671af14d591ede9251acb0085e8017f3705e7 (diff)
downloadlinux-4e8b14526ca7fb046a81c94002c1c43b6fdf0e9b.tar.xz
time: Improve sanity checking of timekeeping inputs
Unexpected behavior could occur if the time is set to a value large enough to overflow a 64bit ktime_t (which is something larger then the year 2262). Also unexpected behavior could occur if large negative offsets are injected via adjtimex. So this patch improves the sanity check timekeeping inputs by improving the timespec_valid() check, and then makes better use of timespec_valid() to make sure we don't set the time to an invalid negative value or one that overflows ktime_t. Note: This does not protect from setting the time close to overflowing ktime_t and then letting natural accumulation cause the overflow. Reported-by: CAI Qian <caiqian@redhat.com> Reported-by: Sasha Levin <levinsasha928@gmail.com> Signed-off-by: John Stultz <john.stultz@linaro.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Prarit Bhargava <prarit@redhat.com> Cc: Zhouping Liu <zliu@redhat.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: stable@vger.kernel.org Link: http://lkml.kernel.org/r/1344454580-17031-1-git-send-email-john.stultz@linaro.org Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'include/linux/time.h')
-rw-r--r--include/linux/time.h22
1 files changed, 20 insertions, 2 deletions
diff --git a/include/linux/time.h b/include/linux/time.h
index c81c5e40fcb5..b0bbd8f0130d 100644
--- a/include/linux/time.h
+++ b/include/linux/time.h
@@ -107,11 +107,29 @@ static inline struct timespec timespec_sub(struct timespec lhs,
return ts_delta;
}
+#define KTIME_MAX ((s64)~((u64)1 << 63))
+#if (BITS_PER_LONG == 64)
+# define KTIME_SEC_MAX (KTIME_MAX / NSEC_PER_SEC)
+#else
+# define KTIME_SEC_MAX LONG_MAX
+#endif
+
/*
* Returns true if the timespec is norm, false if denorm:
*/
-#define timespec_valid(ts) \
- (((ts)->tv_sec >= 0) && (((unsigned long) (ts)->tv_nsec) < NSEC_PER_SEC))
+static inline bool timespec_valid(const struct timespec *ts)
+{
+ /* Dates before 1970 are bogus */
+ if (ts->tv_sec < 0)
+ return false;
+ /* Can't have more nanoseconds then a second */
+ if ((unsigned long)ts->tv_nsec >= NSEC_PER_SEC)
+ return false;
+ /* Disallow values that could overflow ktime_t */
+ if ((unsigned long long)ts->tv_sec >= KTIME_SEC_MAX)
+ return false;
+ return true;
+}
extern void read_persistent_clock(struct timespec *ts);
extern void read_boot_clock(struct timespec *ts);