From: Sasha Levin Subject: [PATCH AUTOSEL 4.9] blk-throttle: fix UAF by deleteing timer in blk_throtl_exit() Date: Thu, 16 Sep 2021 22:35:08 -0400 Message-ID: <20210917023508.816980-1-sashal@kernel.org> Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1631846110; bh=c3XCtVyOOmSN8//YWlQxWHyl3bALKGKJUAe/8BgASdE=; h=From:To:Cc:Subject:Date:From; b=WW56fg2DEIBXn6QuZKh5v44CDC+eBZrYk+P7TzbcmHtRKAPjrVK526CA3Vo9vRkl/ d3j8ZZoTHmzw9eIxMn765ZrH275omKrfH+kuDTfXZSIxZTNx/k0QUdsONRqUUD8E/7 nsckq/HSOwAYlRbLu2Yml9CaH4iDPRwXYv+YLT12dXaNeJEQgY6/fatXsI3My7yHXj +EUHkKZ8gZH4bt3jOpMXFClPptbscn2IBT+s3sqmB7LGiKiwIa/STu2TqG9Y4xToG5 Ki6AZ3g7boIoR2JQL7M62lJ1Rq9LB77z1x+EDqJaktihdL7YXN2rtZXtgWuz97Bmh3 vKBvx1nauHuOA== List-ID: Content-Type: text/plain; charset="us-ascii" To: linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, stable-u79uwXL29TY76Z2rM5mHXA@public.gmane.org Cc: Li Jinlin , Jens Axboe , Sasha Levin , tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-block-u79uwXL29TY76Z2rM5mHXA@public.gmane.org From: Li Jinlin [ Upstream commit 884f0e84f1e3195b801319c8ec3d5774e9bf2710 ] The pending timer has been set up in blk_throtl_init(). However, the timer is not deleted in blk_throtl_exit(). This means that the timer handler may still be running after freeing the timer, which would result in a use-after-free. Fix by calling del_timer_sync() to delete the timer in blk_throtl_exit(). Signed-off-by: Li Jinlin Link: https://lore.kernel.org/r/20210907121242.2885564-1-lijinlin3-hv44wF8Li93QT0dZR+AlfA@public.gmane.org Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin --- block/blk-throttle.c | 1 + 1 file changed, 1 insertion(+) diff --git a/block/blk-throttle.c b/block/blk-throttle.c index 3a4c9a3c1427..6435dc25be0a 100644 --- a/block/blk-throttle.c +++ b/block/blk-throttle.c @@ -1584,6 +1584,7 @@ int blk_throtl_init(struct request_queue *q) void blk_throtl_exit(struct request_queue *q) { BUG_ON(!q->td); + del_timer_sync(&q->td->service_queue.pending_timer); throtl_shutdown_wq(q); blkcg_deactivate_policy(q, &blkcg_policy_throtl); kfree(q->td); -- 2.30.2