This is a note to let you know that I've just added the patch titled block, bfq: fix uaf for bfqq in bic_set_bfqq() to the 5.15-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: block-bfq-fix-uaf-for-bfqq-in-bic_set_bfqq.patch and it can be found in the queue-5.15 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit 8f6579ae02dcda230ba3a5f52becf8a33bd66509 Author: Yu Kuai <yukuai3@xxxxxxxxxx> Date: Mon Jan 30 09:41:36 2023 +0800 block, bfq: fix uaf for bfqq in bic_set_bfqq() [ Upstream commit b600de2d7d3a16f9007fad1bdae82a3951a26af2 ] After commit 64dc8c732f5c ("block, bfq: fix possible uaf for 'bfqq->bic'"), bic->bfqq will be accessed in bic_set_bfqq(), however, in some context bic->bfqq will be freed, and bic_set_bfqq() is called with the freed bic->bfqq. Fix the problem by always freeing bfqq after bic_set_bfqq(). Fixes: 64dc8c732f5c ("block, bfq: fix possible uaf for 'bfqq->bic'") Reported-and-tested-by: Shinichiro Kawasaki <shinichiro.kawasaki@xxxxxxx> Signed-off-by: Yu Kuai <yukuai3@xxxxxxxxxx> Reviewed-by: Jan Kara <jack@xxxxxxx> Link: https://lore.kernel.org/r/20230130014136.591038-1-yukuai1@xxxxxxxxxxxxxxx Signed-off-by: Jens Axboe <axboe@xxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/block/bfq-cgroup.c b/block/bfq-cgroup.c index 4ac6f59a3679..53e275e377a7 100644 --- a/block/bfq-cgroup.c +++ b/block/bfq-cgroup.c @@ -756,8 +756,8 @@ static void *__bfq_bic_change_cgroup(struct bfq_data *bfqd, * request from the old cgroup. */ bfq_put_cooperator(sync_bfqq); - bfq_release_process_ref(bfqd, sync_bfqq); bic_set_bfqq(bic, NULL, true); + bfq_release_process_ref(bfqd, sync_bfqq); } } } diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c index 8d967a67318c..f54554906451 100644 --- a/block/bfq-iosched.c +++ b/block/bfq-iosched.c @@ -5359,9 +5359,11 @@ static void bfq_check_ioprio_change(struct bfq_io_cq *bic, struct bio *bio) bfqq = bic_to_bfqq(bic, false); if (bfqq) { - bfq_release_process_ref(bfqd, bfqq); + struct bfq_queue *old_bfqq = bfqq; + bfqq = bfq_get_queue(bfqd, bio, false, bic, true); bic_set_bfqq(bic, bfqq, false); + bfq_release_process_ref(bfqd, old_bfqq); } bfqq = bic_to_bfqq(bic, true);