4.14-stable review patch. If anyone has any objections, please let me know.
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From: Jens Axboe axboe@kernel.dk
commit 72961c4e6082be79825265d9193272b8a1634dec upstream.
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: aee69d78dec0 ("block, bfq: introduce the BFQ-v0 I/O scheduler as an extra scheduler") Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- block/bfq-iosched.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-)
--- a/block/bfq-iosched.c +++ b/block/bfq-iosched.c @@ -4447,8 +4447,16 @@ static void bfq_prepare_request(struct r 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);