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authorThomas Gleixner <tglx@linutronix.de>2017-06-20 17:37:35 +0200
committerThomas Gleixner <tglx@linutronix.de>2017-06-20 21:33:56 +0200
commit35eb7258c009dc478338e674a5a84d25d0929c56 (patch)
tree7fae943ef2569bf8db0a2e76b60c6027698f3760 /kernel/time/itimer.c
parentd15bc69affc57d7985a01745ca28eafa0772325b (diff)
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 <qiuxishi@huawei.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: John Stultz <john.stultz@linaro.org> Link: http://lkml.kernel.org/r/20170620154113.505981643@linutronix.de
Diffstat (limited to 'kernel/time/itimer.c')
-rw-r--r--kernel/time/itimer.c8
1 files changed, 6 insertions, 2 deletions
diff --git a/kernel/time/itimer.c b/kernel/time/itimer.c
index 9dd7ff5e445a..2ef98a02376a 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);