Commit-ID: 35eb7258c009dc478338e674a5a84d25d0929c56 Gitweb: http://git.kernel.org/tip/35eb7258c009dc478338e674a5a84d25d0929c56 Author: Thomas Gleixner <t...@linutronix.de> AuthorDate: Tue, 20 Jun 2017 17:37:35 +0200 Committer: Thomas Gleixner <t...@linutronix.de> CommitDate: Tue, 20 Jun 2017 21:33:56 +0200
itimer: Make timeval to nsec conversion range limited The expiry time of a itimer is supplied through sys_setitimer() via a struct timeval. The timeval is validated for correctness. In the actual set timer implementation the timeval 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 timeval_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. Reported-by: Xishi Qiu <qiuxi...@huawei.com> Signed-off-by: Thomas Gleixner <t...@linutronix.de> Cc: Peter Zijlstra <pet...@infradead.org> Cc: John Stultz <john.stu...@linaro.org> Link: http://lkml.kernel.org/r/20170620154113.505981...@linutronix.de --- kernel/time/itimer.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/kernel/time/itimer.c b/kernel/time/itimer.c index 9dd7ff5..2ef98a0 100644 --- a/kernel/time/itimer.c +++ b/kernel/time/itimer.c @@ -152,8 +152,12 @@ static void set_cpu_itimer(struct task_struct *tsk, unsigned int clock_id, u64 oval, nval, ointerval, ninterval; struct cpu_itimer *it = &tsk->signal->it[clock_id]; - nval = timeval_to_ns(&value->it_value); - ninterval = timeval_to_ns(&value->it_interval); + /* + * Use the to_ktime conversion because that clamps the maximum + * value to KTIME_MAX and avoid multiplication overflows. + */ + nval = ktime_to_ns(timeval_to_ktime(value->it_value)); + ninterval = ktime_to_ns(timeval_to_ktime(value->it_interval)); spin_lock_irq(&tsk->sighand->siglock);
