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.
