sched/rt: Check integer overflow at usec to nsec conversion

Example of unhandled overflows:

 # echo 18446744073709651 > cpu.rt_runtime_us
 # cat cpu.rt_runtime_us
 99

 # echo 18446744073709900 > cpu.rt_period_us
 # cat cpu.rt_period_us
 348

After this patch they will fail with -EINVAL.

Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/155125501739.293431.5252197504404771496.stgit@buzz
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
index 90fa23d36565d1c76137ab06bedc90bb2a8342a7..1e6b909dca367c58d332a0de3d229932c6bee83f 100644 (file)
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -2555,6 +2555,8 @@ int sched_group_set_rt_runtime(struct task_group *tg, long rt_runtime_us)
        rt_runtime = (u64)rt_runtime_us * NSEC_PER_USEC;
        if (rt_runtime_us < 0)
                rt_runtime = RUNTIME_INF;
+       else if ((u64)rt_runtime_us > U64_MAX / NSEC_PER_USEC)
+               return -EINVAL;
 
        return tg_set_rt_bandwidth(tg, rt_period, rt_runtime);
 }
@@ -2575,6 +2577,9 @@ int sched_group_set_rt_period(struct task_group *tg, u64 rt_period_us)
 {
        u64 rt_runtime, rt_period;
 
+       if (rt_period_us > U64_MAX / NSEC_PER_USEC)
+               return -EINVAL;
+
        rt_period = rt_period_us * NSEC_PER_USEC;
        rt_runtime = tg->rt_bandwidth.rt_runtime;