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authorJohn Stultz <john.stultz@linaro.org>2012-09-11 20:49:51 -0400
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2012-10-02 09:47:44 -0700
commit44fa9a0111168832510f8add6d589e73eac6793d (patch)
treed147ce4877e360198c3e1e8f282aa0df8fd13846 /kernel
parent81cee4e9e6329bff1adafefed0ff2db85b360a41 (diff)
time: Improve sanity checking of timekeeping inputs
commit 4e8b14526ca7fb046a81c94002c1c43b6fdf0e9b upstream 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> Link: http://lkml.kernel.org/r/1344454580-17031-1-git-send-email-john.stultz@linaro.org Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: John Stultz <john.stultz@linaro.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/time/timekeeping.c26
1 files changed, 24 insertions, 2 deletions
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index 678ae3184efd..bfa6be73873c 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -382,7 +382,7 @@ int do_settimeofday(const struct timespec *tv)
struct timespec ts_delta;
unsigned long flags;
- if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)
+ if (!timespec_valid(tv))
return -EINVAL;
write_seqlock_irqsave(&xtime_lock, flags);
@@ -417,6 +417,8 @@ EXPORT_SYMBOL(do_settimeofday);
int timekeeping_inject_offset(struct timespec *ts)
{
unsigned long flags;
+ struct timespec tmp;
+ int ret = 0;
if ((unsigned long)ts->tv_nsec >= NSEC_PER_SEC)
return -EINVAL;
@@ -425,9 +427,16 @@ int timekeeping_inject_offset(struct timespec *ts)
timekeeping_forward_now();
+ tmp = timespec_add(xtime, *ts);
+ if (!timespec_valid(&tmp)) {
+ ret = -EINVAL;
+ goto error;
+ }
+
xtime = timespec_add(xtime, *ts);
wall_to_monotonic = timespec_sub(wall_to_monotonic, *ts);
+error: /* even if we error out, we forwarded the time, so call update */
timekeeping_update(true);
write_sequnlock_irqrestore(&xtime_lock, flags);
@@ -435,7 +444,7 @@ int timekeeping_inject_offset(struct timespec *ts)
/* signal hrtimers about time change */
clock_was_set();
- return 0;
+ return ret;
}
EXPORT_SYMBOL(timekeeping_inject_offset);
@@ -582,7 +591,20 @@ void __init timekeeping_init(void)
struct timespec now, boot;
read_persistent_clock(&now);
+ if (!timespec_valid(&now)) {
+ pr_warn("WARNING: Persistent clock returned invalid value!\n"
+ " Check your CMOS/BIOS settings.\n");
+ now.tv_sec = 0;
+ now.tv_nsec = 0;
+ }
+
read_boot_clock(&boot);
+ if (!timespec_valid(&boot)) {
+ pr_warn("WARNING: Boot clock returned invalid value!\n"
+ " Check your CMOS/BIOS settings.\n");
+ boot.tv_sec = 0;
+ boot.tv_nsec = 0;
+ }
write_seqlock_irqsave(&xtime_lock, flags);