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bfq-iosched: ensure to clear bic/bfqq pointers when preparing request

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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 <oleksandr@natalenko.name>
Reported-by: Kees Cook <keescook@chromium.org>
Cc: stable@vger.kernel.org
Fixes: aee69d78de ("block, bfq: introduce the BFQ-v0 I/O scheduler as an extra scheduler")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Jens Axboe 2018-04-17 17:08:52 -06:00
parent f4560231ec
commit 72961c4e60
1 changed files with 9 additions and 1 deletions
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10
block/bfq-iosched.c
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@ -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);