From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 11F2AE56C for ; Mon, 15 May 2023 16:44:37 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6B3AAC433EF; Mon, 15 May 2023 16:44:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1684169076; bh=P3XZNrWh6s3NUfI9UE0cFFSDabRO/GJJKlNZnZKAmug=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Oaf20CTEdgwNV0jaL2XGNRQxKOf7UKi9wG297ssQM3fOO4Nx17mwoaBdv5yOgWDhF Exrzl0aD/uB+2/hqV/WMZmviZ83dCPGMdlOSLzjkrQhMwjOZ8cVhKXqsbxR2gPf/os bLijvVxxkeI+Tv+Z/Nas62D6ca/XsTbm4oKeurzI= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Zheng Zhang , Mike Snitzer Subject: [PATCH 4.19 135/191] dm ioctl: fix nested locking in table_clear() to remove deadlock concern Date: Mon, 15 May 2023 18:26:12 +0200 Message-Id: <20230515161712.284566344@linuxfoundation.org> X-Mailer: git-send-email 2.40.1 In-Reply-To: <20230515161707.203549282@linuxfoundation.org> References: <20230515161707.203549282@linuxfoundation.org> User-Agent: quilt/0.67 Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Mike Snitzer commit 3d32aaa7e66d5c1479a3c31d6c2c5d45dd0d3b89 upstream. syzkaller found the following problematic rwsem locking (with write lock already held): down_read+0x9d/0x450 kernel/locking/rwsem.c:1509 dm_get_inactive_table+0x2b/0xc0 drivers/md/dm-ioctl.c:773 __dev_status+0x4fd/0x7c0 drivers/md/dm-ioctl.c:844 table_clear+0x197/0x280 drivers/md/dm-ioctl.c:1537 In table_clear, it first acquires a write lock https://elixir.bootlin.com/linux/v6.2/source/drivers/md/dm-ioctl.c#L1520 down_write(&_hash_lock); Then before the lock is released at L1539, there is a path shown above: table_clear -> __dev_status -> dm_get_inactive_table -> down_read https://elixir.bootlin.com/linux/v6.2/source/drivers/md/dm-ioctl.c#L773 down_read(&_hash_lock); It tries to acquire the same read lock again, resulting in the deadlock problem. Fix this by moving table_clear()'s __dev_status() call to after its up_write(&_hash_lock); Cc: stable@vger.kernel.org Reported-by: Zheng Zhang Signed-off-by: Mike Snitzer Signed-off-by: Greg Kroah-Hartman --- drivers/md/dm-ioctl.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) --- a/drivers/md/dm-ioctl.c +++ b/drivers/md/dm-ioctl.c @@ -1410,11 +1410,12 @@ static int table_clear(struct file *filp hc->new_map = NULL; } - param->flags &= ~DM_INACTIVE_PRESENT_FLAG; - - __dev_status(hc->md, param); md = hc->md; up_write(&_hash_lock); + + param->flags &= ~DM_INACTIVE_PRESENT_FLAG; + __dev_status(md, param); + if (old_map) { dm_sync_table(md); dm_table_destroy(old_map);