perf: Fix race in swevent hash
authorPeter Zijlstra <peterz@infradead.org>
Tue, 15 Dec 2015 12:49:05 +0000 (13:49 +0100)
committerIngo Molnar <mingo@kernel.org>
Wed, 6 Jan 2016 09:52:39 +0000 (10:52 +0100)
commit12ca6ad2e3a896256f086497a7c7406a547ee373
tree96f15b0a7c6622da00161b2b66ac6fb78019cfbe
parentc127449944659543e5e2423002f08f0af98dba5c
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.

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>
kernel/events/core.c