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[3.13,148/212] perf: Limit perf_event_attr::sample_period to 63 bits

Message ID 1403041506-13646-149-git-send-email-kamal@canonical.com
State New
Headers show

Commit Message

Kamal Mostafa June 17, 2014, 9:44 p.m. UTC 
3.13.11.4 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Peter Zijlstra <peterz@infradead.org>

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.

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: Kamal Mostafa <kamal@canonical.com>
---
 kernel/events/core.c | 3 +++
 1 file changed, 3 insertions(+)
diff mbox

Patch

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 6ed1163..ad33a96 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -6997,6 +6997,9 @@  SYSCALL_DEFINE5(perf_event_open,
 	if (attr.freq) {
 		if (attr.sample_freq > sysctl_perf_event_sample_rate)
 			return -EINVAL;
+	} else {
+		if (attr.sample_period & (1ULL << 63))
+			return -EINVAL;
 	}
 
 	/*