4.16-stable review patch. If anyone has any objections, please let me know.
------------------
From: Jens Axboe <ax...@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 <oleksa...@natalenko.name>
Reported-by: Kees Cook <keesc...@chromium.org>
Cc: sta...@vger.kernel.org
Fixes: aee69d78dec0 ("block, bfq: introduce the BFQ-v0 I/O scheduler as an
extra scheduler")
Signed-off-by: Jens Axboe <ax...@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
block/bfq-iosched.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)
--- a/block/bfq-iosched.c
+++ b/block/bfq-iosched.c
@@ -4911,8 +4911,16 @@ 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);
