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 9423218658 for ; Wed, 20 Sep 2023 11:50:30 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1788AC433C7; Wed, 20 Sep 2023 11:50:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1695210630; bh=aUq/5WVFouFn+L5zSQ2YTbMGplzl05jxCm+Jw/8nF+k=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=l+dGZW2wcGIusRbOMfiM8swYhkQ+cGieVJiYfVVzN6woL9Fbhc8ZbMz6/Rgw4ZlrD SJeUzJs3VGSicK2dtFaJ6IXkLUZtjWvXBjzeCtLpFnhxOXtMO2QIJZH830I+9igxOX yc/sWj/SJVuY3kksySc3p4fgCKqW61q6NX5LLdnU= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Yu Kuai , Song Liu , Sasha Levin Subject: [PATCH 6.5 146/211] md: dont dereference mddev after export_rdev() Date: Wed, 20 Sep 2023 13:29:50 +0200 Message-ID: <20230920112850.380502337@linuxfoundation.org> X-Mailer: git-send-email 2.42.0 In-Reply-To: <20230920112845.859868994@linuxfoundation.org> References: <20230920112845.859868994@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.5-stable review patch. If anyone has any objections, please let me know. ------------------ From: Yu Kuai [ Upstream commit 7deac114be5fb25a4e865212ed0feaf5f85f2a28 ] Except for initial reference, mddev->kobject is referenced by rdev->kobject, and if the last rdev is freed, there is no guarantee that mddev is still valid. Hence mddev should not be used anymore after export_rdev(). This problem can be triggered by following test for mdadm at very low rate: New file: mdadm/tests/23rdev-lifetime devname=${dev0##*/} devt=`cat /sys/block/$devname/dev` pid="" runtime=2 clean_up_test() { pill -9 $pid echo clear > /sys/block/md0/md/array_state } trap 'clean_up_test' EXIT add_by_sysfs() { while true; do echo $devt > /sys/block/md0/md/new_dev done } remove_by_sysfs(){ while true; do echo remove > /sys/block/md0/md/dev-${devname}/state done } echo md0 > /sys/module/md_mod/parameters/new_array || die "create md0 failed" add_by_sysfs & pid="$pid $!" remove_by_sysfs & pid="$pid $!" sleep $runtime exit 0 Test cmd: ./test --save-logs --logdir=/tmp/ --keep-going --dev=loop --tests=23rdev-lifetime Test result: general protection fault, probably for non-canonical address 0x6b6b6b6b6b6b6bcb: 0000 [#4] PREEMPT SMP CPU: 0 PID: 1292 Comm: test Tainted: G D W 6.5.0-rc2-00121-g01e55c376936 #562 RIP: 0010:md_wakeup_thread+0x9e/0x320 [md_mod] Call Trace: mddev_unlock+0x1b6/0x310 [md_mod] rdev_attr_store+0xec/0x190 [md_mod] sysfs_kf_write+0x52/0x70 kernfs_fop_write_iter+0x19a/0x2a0 vfs_write+0x3b5/0x770 ksys_write+0x74/0x150 __x64_sys_write+0x22/0x30 do_syscall_64+0x40/0x90 entry_SYSCALL_64_after_hwframe+0x63/0xcd Fix this problem by don't dereference mddev after export_rdev(). Fixes: 3ce94ce5d05a ("md: fix duplicate filename for rdev") Signed-off-by: Yu Kuai Signed-off-by: Song Liu Link: https://lore.kernel.org/r/20230825025532.1523008-2-yukuai1@huaweicloud.com Signed-off-by: Sasha Levin --- drivers/md/md.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/drivers/md/md.c b/drivers/md/md.c index 2a4a3d3039fae..fba2809cd384a 100644 --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -798,14 +798,14 @@ void mddev_unlock(struct mddev *mddev) } else mutex_unlock(&mddev->reconfig_mutex); + md_wakeup_thread(mddev->thread); + wake_up(&mddev->sb_wait); + list_for_each_entry_safe(rdev, tmp, &delete, same_set) { list_del_init(&rdev->same_set); kobject_del(&rdev->kobj); export_rdev(rdev, mddev); } - - md_wakeup_thread(mddev->thread); - wake_up(&mddev->sb_wait); } EXPORT_SYMBOL_GPL(mddev_unlock); -- 2.40.1