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| author |   Thomas Gleixner <tglx@linutronix.de> | 2017-06-20 17:37:36 +0200 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2017-06-20 21:33:56 +0200 |
| commit | 098b0e01a91c42aaaf0425605cd126b03fcb0bcf (patch) | |
| tree | d936fa77c10117b58f5a47f789745bc88b093c75 /kernel/time | |
| parent | itimer: Make timeval to nsec conversion range limited (diff) | |
| download | linux-dev-098b0e01a91c42aaaf0425605cd126b03fcb0bcf.tar.xz linux-dev-098b0e01a91c42aaaf0425605cd126b03fcb0bcf.zip | |
posix-cpu-timers: Make timespec to nsec conversion safe
The expiry time of a posix cpu timer is supplied through sys_timer_set()
via a struct timespec. The timespec is validated for correctness.
In the actual set timer implementation the timespec is converted to a
scalar nanoseconds value. If the tv_sec part of the time spec is large
enough the conversion to nanoseconds (sec * NSEC_PER_SEC) overflows 64bit.
Mitigate that by using the timespec_to_ktime() conversion function, which
checks the tv_sec part for a potential mult overflow and clamps the result
to KTIME_MAX, which is about 292 years.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Xishi Qiu <qiuxishi@huawei.com>
Cc: John Stultz <john.stultz@linaro.org>
Link: http://lkml.kernel.org/r/20170620154113.588276707@linutronix.de
Diffstat (limited to 'kernel/time')
| -rw-r--r-- | kernel/time/posix-cpu-timers.c | 6 |
1 files changed, 5 insertions, 1 deletions
diff --git a/kernel/time/posix-cpu-timers.c b/kernel/time/posix-cpu-timers.c index 9df618ee64cf..60cb24ac9ebc 100644 --- a/kernel/time/posix-cpu-timers.c +++ b/kernel/time/posix-cpu-timers.c @@ -580,7 +580,11 @@ static int posix_cpu_timer_set(struct k_itimer *timer, int timer_flags, WARN_ON_ONCE(p == NULL); - new_expires = timespec64_to_ns(&new->it_value); + /* + * Use the to_ktime conversion because that clamps the maximum + * value to KTIME_MAX and avoid multiplication overflows. + */ + new_expires = ktime_to_ns(timespec64_to_ktime(new->it_value)); /* * Protect against sighand release/switch in exit/exec and p->cpu_timers |