From: Yu Kuai yukuai3@huawei.com
[ Upstream commit 246cf66e300b76099b5dbd3fdd39e9a5dbc53f02 ]
Commit 64dc8c732f5c ("block, bfq: fix possible uaf for 'bfqq->bic'") will access 'bic->bfqq' in bic_set_bfqq(), however, bfq_exit_icq_bfqq() can free bfqq first, and then call bic_set_bfqq(), which will cause uaf.
Fix the problem by moving bfq_exit_bfqq() behind bic_set_bfqq().
Fixes: 64dc8c732f5c ("block, bfq: fix possible uaf for 'bfqq->bic'") Reported-by: Yi Zhang yi.zhang@redhat.com Signed-off-by: Yu Kuai yukuai3@huawei.com Link: https://lore.kernel.org/r/20221226030605.1437081-1-yukuai1@huaweicloud.com Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Sasha Levin sashal@kernel.org Signed-off-by: Khazhismel Kumykov khazhy@google.com --- block/bfq-iosched.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c index afaededb3c49..0a53b653a7e2 100644 --- a/block/bfq-iosched.c +++ b/block/bfq-iosched.c @@ -4983,8 +4983,8 @@ static void bfq_exit_icq_bfqq(struct bfq_io_cq *bic, bool is_sync) unsigned long flags;
spin_lock_irqsave(&bfqd->lock, flags); - bfq_exit_bfqq(bfqd, bfqq); bic_set_bfqq(bic, NULL, is_sync); + bfq_exit_bfqq(bfqd, bfqq); spin_unlock_irqrestore(&bfqd->lock, flags); } }