From: Yu Kuai Date: Mon, 30 Jan 2023 01:41:36 +0000 (+0800) Subject: block, bfq: fix uaf for bfqq in bic_set_bfqq() X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=b600de2d7d3a16f9007fad1bdae82a3951a26af2;p=linux.git block, bfq: fix uaf for bfqq in bic_set_bfqq() 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 Signed-off-by: Yu Kuai Reviewed-by: Jan Kara Link: https://lore.kernel.org/r/20230130014136.591038-1-yukuai1@huaweicloud.com Signed-off-by: Jens Axboe --- diff --git a/block/bfq-cgroup.c b/block/bfq-cgroup.c index 7d9b15f0dbd57..0fbde0fc06287 100644 --- a/block/bfq-cgroup.c +++ b/block/bfq-cgroup.c @@ -769,8 +769,8 @@ 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 ccf2204477a57..380e9bda2e57c 100644 --- a/block/bfq-iosched.c +++ b/block/bfq-iosched.c @@ -5425,9 +5425,11 @@ 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);