[PATCH 1/2] perf ioctl: Add check for the sample_period value

[Ravi Bangoria]

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;
+
        event_function_call(event, __perf_event_period, &value);
 
        return 0;
-- 
2.20.1