Ravi Bangoria <ravi.bango...@linux.ibm.com> writes: > On 5/13/19 2:26 PM, Peter Zijlstra wrote: >> On Mon, May 13, 2019 at 09:42:13AM +0200, Peter Zijlstra wrote: >>> On Sat, May 11, 2019 at 08:12:16AM +0530, Ravi Bangoria wrote: >>>> Add a check for sample_period value sent from userspace. Negative >>>> value does not make sense. And in powerpc arch code this could cause >>>> a recursive PMI leading to a hang (reported when running perf-fuzzer). >>>> >>>> Signed-off-by: Ravi Bangoria <ravi.bango...@linux.ibm.com> >>>> --- >>>> kernel/events/core.c | 3 +++ >>>> 1 file changed, 3 insertions(+) >>>> >>>> diff --git a/kernel/events/core.c b/kernel/events/core.c >>>> index abbd4b3b96c2..e44c90378940 100644 >>>> --- a/kernel/events/core.c >>>> +++ b/kernel/events/core.c >>>> @@ -5005,6 +5005,9 @@ static int perf_event_period(struct perf_event >>>> *event, u64 __user *arg) >>>> if (perf_event_check_period(event, value)) >>>> return -EINVAL; >>>> >>>> + if (!event->attr.freq && (value & (1ULL << 63))) >>>> + return -EINVAL; >>> >>> Well, perf_event_attr::sample_period is __u64. Would not be the site >>> using it as signed be the one in error? >> >> You forgot to mention commit: 0819b2e30ccb9, so I guess this just makes >> it consistent and is fine. >> > > Yeah, I was about to reply :)
I've taken patch 2. You should probably do a v2 of patch 1 with an updated change log that explains things fully? cheers
