diff options
| author | Peter Zijlstra <peterz@infradead.org> | 2016-11-08 22:34:03 +0100 |
|---|---|---|
| committer | Moyster <oysterized@gmail.com> | 2016-11-17 12:13:07 +0100 |
| commit | 9904371998096f26098595f5c82674ffaceee573 (patch) | |
| tree | 17d36c7bfbd103718e98f7f2c9b6fada01bfc940 /kernel/events | |
| parent | 74d74bb276ba1f484e6719b1a513aa8ad0c208d5 (diff) | |
perf: Fix race in swevent hash
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.
Change-Id: I751faf3215bbdaa6b6358f3a752bdd24126cfa0b
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>
Diffstat (limited to 'kernel/events')
| -rw-r--r-- | kernel/events/core.c | 8 |
1 files changed, 0 insertions, 8 deletions
diff --git a/kernel/events/core.c b/kernel/events/core.c index 94936639e..7bf38780e 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -5521,7 +5521,6 @@ 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; @@ -7615,14 +7614,7 @@ 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); - perf_event_exit_cpu_context(cpu); - - mutex_lock(&swhash->hlist_mutex); - swhash->online = false; - swevent_hlist_release(swhash); - mutex_unlock(&swhash->hlist_mutex); } #else static inline void perf_event_exit_cpu(int cpu) { } |