perf: Limit perf_event_attr::sample_period to 63 bits
commit 0819b2e30ccb93edf04876237b6205eef84ec8d2 upstream.
Vince reported that using a large sample_period (one with bit 63 set)
results in wreckage since while the sample_period is fundamentally
unsigned (negative periods don't make sense) the way we implement
things very much rely on signed logic.
So limit sample_period to 63 bits to avoid tripping over this.
Change-Id: I80055207c31cb1f321aea305950c05428006d90e
Original-Change-Id: I6f620812992a0e76bb500dd51fdcdde219779306
Reported-by: Vince Weaver <vincent.weaver@maine.edu>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/n/tip-p25fhunibl4y3qi0zuqmyf4b@git.kernel.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 910698e..e9a4b7b 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -6269,6 +6269,9 @@
if (attr.freq) {
if (attr.sample_freq > sysctl_perf_event_sample_rate)
return -EINVAL;
+ } else {
+ if (attr.sample_period & (1ULL << 63))
+ return -EINVAL;
}
/*