This is a note to let you know that I've just added the patch titled
perf: Limit perf_event_attr::sample_period to 63 bits
to the 3.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
perf-limit-perf_event_attr-sample_period-to-63-bits.patch
and it can be found in the queue-3.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.
>From 0819b2e30ccb93edf04876237b6205eef84ec8d2 Mon Sep 17 00:00:00 2001
From: Peter Zijlstra <[email protected]>
Date: Thu, 15 May 2014 20:23:48 +0200
Subject: perf: Limit perf_event_attr::sample_period to 63 bits
From: Peter Zijlstra <[email protected]>
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 <[email protected]>
Signed-off-by: Peter Zijlstra <[email protected]>
Link: http://lkml.kernel.org/n/[email protected]
Signed-off-by: Thomas Gleixner <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
kernel/events/core.c | 3 +++
1 file changed, 3 insertions(+)
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -6356,6 +6356,9 @@ 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;
}
/*
Patches currently in stable-queue which might be from [email protected] are
queue-3.4/sched-use-cpupri_nr_priorities-instead-of-max_rt_prio-in-cpupri-check.patch
queue-3.4/perf-prevent-false-warning-in-perf_swevent_add.patch
queue-3.4/perf-fix-race-in-removing-an-event.patch
queue-3.4/perf-limit-perf_event_attr-sample_period-to-63-bits.patch
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