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disallow clock_settime too far in the future to avoid panic

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clock_ts_to_ct has a KASSERT that the converted year fits into four
digits.  By default (sysctl debug.allow_insane_settime is 0) the kernel
disallows a time too far in the future, using a value of 9999 366-day
years.  However, clock_settime is epoch-relative and the assertion will
fail with a tv_sec corresponding to some 8030 years.

Avoid trying to be too clever, and just use a limit of 8000 365-day
years past the epoch.

Submitted by:	Heqing Yan <scottieyan@gmail.com>
Reported by:	Syzkaller (https://github.com/google/syzkaller)
MFC after:	1 week
Sponsored by:	The FreeBSD Foundation
This commit is contained in:
Ed Maste 2017-11-14 18:18:18 +00:00
parent c52ef9bbff
commit 81d606f52e
1 changed files with 1 additions and 1 deletions
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2
sys/kern/kern_time.c
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@ -408,7 +408,7 @@ kern_clock_settime(struct thread *td, clockid_t clock_id, struct timespec *ats)
if (ats->tv_nsec < 0 || ats->tv_nsec >= 1000000000 ||
ats->tv_sec < 0)
return (EINVAL);
if (!allow_insane_settime && ats->tv_sec > 9999ULL * 366 * 24 * 60 * 60)
if (!allow_insane_settime && ats->tv_sec > 8000ULL * 365 * 24 * 60 * 60)
return (EINVAL);
/* XXX Don't convert nsec->usec and back */
TIMESPEC_TO_TIMEVAL(&atv, ats);