diff options
| author | Peter Zijlstra <peterz@infradead.org> | 2016-09-12 13:35:44 -0700 |
|---|---|---|
| committer | Pat Tjin <pattjin@google.com> | 2016-09-19 18:53:28 +0000 |
| commit | 787b5eaf56017c49759c517038080cda41f0a5fe (patch) | |
| tree | b2713de1c0e18b083cec07809fec91ecb92b764f | |
| parent | 5afe518fe58acb1faec5e1b3793746133fca5e0b (diff) | |
| download | x86_64-android-x86_64-fugu-3.10-nougat.tar.gz | |
BACKPORT: perf: Fix race in swevent hashandroid-7.0.0_r0.32android-x86_64-fugu-3.10-nougat
(cherry picked from commit 12ca6ad2e3a896256f086497a7c7406a547ee373)
There's a race on CPU unplug where we free the swevent hash array
while it can still have events on. This will result in a
use-after-free which is BAD.
Simply do not free the hash array on unplug. This leaves the thing
around and no use-after-free takes place.
When the last swevent dies, we do a for_each_possible_cpu() iteration
anyway to clean these up, at which time we'll free it, so no leakage
will occur.
Reported-by: Sasha Levin <sasha.levin@oracle.com>
Tested-by: Sasha Levin <sasha.levin@oracle.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Change-Id: I4972ce74211b6504ff61325c4a4f7b088306d1f9
Bug: 30952077
Signed-off-by: Yueyao (Nathan) Zhu <yueyao@google.com>
| -rw-r--r-- | kernel/events/core.c | 7 |
1 files changed, 0 insertions, 7 deletions
diff --git a/kernel/events/core.c b/kernel/events/core.c index 2efa181e46e0..826b77ac7af4 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -5372,7 +5372,6 @@ static int swevent_hlist_get_cpu(struct perf_event *event, int cpu) int err = 0; mutex_lock(&swhash->hlist_mutex); - if (!swevent_hlist_deref(swhash) && cpu_online(cpu)) { struct swevent_hlist *hlist; @@ -7462,12 +7461,6 @@ static void perf_event_exit_cpu_context(int cpu) static void perf_event_exit_cpu(int cpu) { - struct swevent_htable *swhash = &per_cpu(swevent_htable, cpu); - - mutex_lock(&swhash->hlist_mutex); - swevent_hlist_release(swhash); - mutex_unlock(&swhash->hlist_mutex); - perf_event_exit_cpu_context(cpu); } #else |