From bce6133b09013f70d41a678d262a12147ed43889 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Tue, 18 Aug 2015 14:54:59 -0700 Subject: cfq-iosched: fix oom cfq_queue ref leak in cfq_set_request() If the cfq_queue cached in cfq_io_cq is the oom one, cfq_set_request() replaces it by invoking cfq_get_queue() again without putting the oom queue leaking the reference it was holding. While oom queues are not released through reference counting, they're still reference counted and this can theoretically lead to the reference count overflowing and incorrectly invoke the usual release path on it. Fix it by making cfq_set_request() put the ref it was holding. Signed-off-by: Tejun Heo Acked-by: Jeff Moyer Cc: Vivek Goyal Cc: Arianna Avanzini Signed-off-by: Jens Axboe --- block/cfq-iosched.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'block') diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index baf0b706169d..8acfb7a3b2ba 100644 --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -4299,6 +4299,8 @@ cfq_set_request(struct request_queue *q, struct request *rq, struct bio *bio, new_queue: cfqq = cic_to_cfqq(cic, is_sync); if (!cfqq || cfqq == &cfqd->oom_cfqq) { + if (cfqq) + cfq_put_queue(cfqq); cfqq = cfq_get_queue(cfqd, is_sync, cic, bio, gfp_mask); cic_set_cfqq(cic, cfqq, is_sync); } else { -- cgit v1.2.3-58-ga151