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authorPeter Zijlstra <peterz@infradead.org>2015-12-15 13:49:05 +0100
committerSimon Shields <keepcalm444@gmail.com>2016-11-11 13:26:51 +1100
commitb794ccaf33cd5ac7afa88df3bccaf11b4f1a0d55 (patch)
tree18216eee4f158cf61ac83b385ffe276ce8e6bbfc
parent4c72b649cb557ff8b613b94bd68471ecfb42f0fb (diff)
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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>
-rw-r--r--kernel/events/core.c7
1 files changed, 0 insertions, 7 deletions
diff --git a/kernel/events/core.c b/kernel/events/core.c
index acdc087..3c75ec6 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -5416,7 +5416,6 @@ 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;
@@ -7309,12 +7308,6 @@ 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