Thomas, Ingo,
This is against tip/timers/urgent. Let me know
if you'd like to see any further changes
-john
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 2264).
So check timekeeping inputs to make sure we don't set
the time to a value 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.
Cc: Ingo Molnar <mi...@kernel.org>
Cc: Peter Zijlstra <a.p.zijls...@chello.nl>
Cc: Prarit Bhargava <pra...@redhat.com>
Cc: Thomas Gleixner <t...@linutronix.de>
Cc: Zhouping Liu <z...@redhat.com>
Cc: CAI Qian <caiq...@redhat.com>
Cc: sta...@vger.kernel.org
Reported-by: CAI Qian <caiq...@redhat.com>
Signed-off-by: John Stultz <john.stu...@linaro.org>
---
kernel/time/timekeeping.c | 26 +++++++++++++++++++++++++-
1 file changed, 25 insertions(+), 1 deletion(-)
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index 2988bc8..6a31968 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -88,6 +88,8 @@ __cacheline_aligned_in_smp DEFINE_SEQLOCK(xtime_lock);
/* flag for if timekeeping is suspended */
int __read_mostly timekeeping_suspended;
+#define TWENTY_YEARS (20LL*365*24*60*60)
+
static inline void tk_normalize_xtime(struct timekeeper *tk)
{
while (tk->xtime_nsec >= ((u64)NSEC_PER_SEC << tk->shift)) {
@@ -430,6 +432,9 @@ int do_settimeofday(const struct timespec *tv)
if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)
return -EINVAL;
+ if ((unsigned long long)tv->tv_sec >= KTIME_SEC_MAX)
+ return -EINVAL;
+
write_seqlock_irqsave(&tk->lock, flags);
timekeeping_forward_now(tk);
@@ -463,6 +468,8 @@ int timekeeping_inject_offset(struct timespec *ts)
{
struct timekeeper *tk = &timekeeper;
unsigned long flags;
+ long long tmp;
+ int ret = 0;
if ((unsigned long)ts->tv_nsec >= NSEC_PER_SEC)
return -EINVAL;
@@ -471,10 +478,17 @@ int timekeeping_inject_offset(struct timespec *ts)
timekeeping_forward_now(tk);
+ /* Make sure the increased value won't cause ktime_t trouble */
+ tmp = tk->xtime_sec + ts->tv_sec;
+ if (tmp >= KTIME_SEC_MAX) {
+ ret = -EINVAL;
+ goto error;
+ }
tk_xtime_add(tk, ts);
tk_set_wall_to_mono(tk, timespec_sub(tk->wall_to_monotonic, *ts));
+error: /* even if we error out, we forwarded the time, so call update */
timekeeping_update(tk, true);
write_sequnlock_irqrestore(&tk->lock, flags);
@@ -482,7 +496,7 @@ int timekeeping_inject_offset(struct timespec *ts)
/* signal hrtimers about time change */
clock_was_set();
- return 0;
+ return ret;
}
EXPORT_SYMBOL(timekeeping_inject_offset);
@@ -651,6 +665,16 @@ void __init timekeeping_init(void)
read_persistent_clock(&now);
read_boot_clock(&boot);
+ /*
+ * Check to make sure the persistent clock
+ * didn't return something crazy.
+ */
+ if (now.tv_sec > (KTIME_SEC_MAX - TWENTY_YEARS)) {
+ pr_warn("WARNING: Persistent clock returned > year 2242!\n"
+ " Check your CMOS/BIOS settings.\n");
+ now.tv_sec = KTIME_SEC_MAX - TWENTY_YEARS;
+ }
+
seqlock_init(&tk->lock);
ntp_init();
--
1.7.9.5
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