From 72961c4e6082be79825265d9193272b8a1634dec Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Tue, 17 Apr 2018 17:08:52 -0600 Subject: [PATCH] bfq-iosched: ensure to clear bic/bfqq pointers when preparing request Even if we don't have an IO context attached to a request, we still need to clear the priv[0..1] pointers, as they could be pointing to previously used bic/bfqq structures. If we don't do so, we'll either corrupt memory on dispatching a request, or cause an imbalance in counters. Inspired by a fix from Kees. Reported-by: Oleksandr Natalenko Reported-by: Kees Cook Cc: stable@vger.kernel.org Fixes: aee69d78dec0 ("block, bfq: introduce the BFQ-v0 I/O scheduler as an extra scheduler") Signed-off-by: Jens Axboe --- block/bfq-iosched.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c index f0ecd98509d8..771ae9730ac6 100644 --- a/block/bfq-iosched.c +++ b/block/bfq-iosched.c @@ -4934,8 +4934,16 @@ static void bfq_prepare_request(struct request *rq, struct bio *bio) bool new_queue = false; bool bfqq_already_existing = false, split = false; - if (!rq->elv.icq) + /* + * Even if we don't have an icq attached, we should still clear + * the scheduler pointers, as they might point to previously + * allocated bic/bfqq structs. + */ + if (!rq->elv.icq) { + rq->elv.priv[0] = rq->elv.priv[1] = NULL; return; + } + bic = icq_to_bic(rq->elv.icq); spin_lock_irq(&bfqd->lock); -- 2.30.2