From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp153-170.sina.com.cn (smtp153-170.sina.com.cn [61.135.153.170]) (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 4B7103DAADE for ; Fri, 28 Aug 2026 10:40:12 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=61.135.153.170 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787913622; cv=none; b=DLw6sQiM8A/SGXxUzt0LefI65fffojlzisND6A7PjMqNPJ34x+g5rKaRwWPlUfZZ1ecVOrIae5g24Me3IzsFM455dX8FK9WswpxUpTHXG5z9J7/66Eu+2pVfV4vhJNCiRt8yT7xzAAINyo4Trr5cWvIlZ7ztD1jNE6VuFgfR2S4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787913622; c=relaxed/simple; bh=YAUw6g07BXmtWFoD9VCDQoHbfUdwW08Jivc6mI48GEI=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=MOd/jE5IHxqhgI1riVUpc7i4wWudN7bg5XkdXAkYHDwNmBHPqgVmBS/48waMmG8YHI3/pkkCyS449f6R+8GNJJp69KV+bHs99qAJlPfCVFhkLt5SYr7AIp4vDPtlV5vBmk9HeQ5UBVosF0uCEjYjLn20JsAswIxPIfOykyeVnto= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=sina.com; spf=pass smtp.mailfrom=sina.com; dkim=pass (1024-bit key) header.d=sina.com header.i=@sina.com header.b=vc85yMWz; arc=none smtp.client-ip=61.135.153.170 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=sina.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=sina.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=sina.com header.i=@sina.com header.b="vc85yMWz" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sina.com; s=201208; t=1787913613; bh=hXY+WbbG19Rh8/V32bq6DCv/4+Yy1+y5L54TzXJtYtU=; h=From:Subject:Date:Message-ID; b=vc85yMWzuLZVtd/FhgOkMZqCxPTcwIOCQ15awDvkRdN65GrxvKv1FkA8N78tUjsIP 5jVtd3vDErBuUHXGAFokuBvD8ltHbAGrA7p5LN//jHOG5W+v7J64DGOo8F+wvzY6ev QeJIL6vVgSaVXuEwFZP0Mi6q4QGfhk5LUk9pr2xE= X-SMAIL-HELO: lxu-ped-host.. Received: from unknown (HELO lxu-ped-host..)([111.198.231.89]) by sina.com (10.54.253.34) with ESMTP id 6A91657D00006DC1; Fri, 28 Aug 2026 18:40:03 +0800 (CST) X-Sender: eadavis@sina.com X-Auth-ID: eadavis@sina.com Authentication-Results: sina.com; spf=none smtp.mailfrom=eadavis@sina.com; dkim=none header.i=none; dmarc=none action=none header.from=eadavis@sina.com X-SMAIL-MID: 3546146291675 X-SMAIL-UIID: A782ECB0474B43B095A6A99C9A395CF2-20260828-184003-1 From: Edward Adam Davis To: syzbot+3fe892ea5fc292e1353f@syzkaller.appspotmail.com Cc: song@kernel.org, yukuai@fygo.io, magiclinan@didiglobal.com, xiao@kernel.org, linux-raid@vger.kernel.org, linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com Subject: [PATCH] md/raid1: prevent a race between write and stop request Date: Fri, 28 Aug 2026 18:39:57 +0800 Message-ID: <20260828103957.245658-1-eadavis@sina.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <6a908777.1d9ded08.62e62.00da.GAE@google.com> References: <6a908777.1d9ded08.62e62.00da.GAE@google.com> Precedence: bulk X-Mailing-List: linux-raid@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit A race condition exists between write and stop requests, leading to a null-ptr-deref in [1]. CPU0 CPU1 ==== ==== md_submit_bio() md_handle_request() do_md_stop()__md_stop() raid1_make_request() __md_stop() raid1_write_request() mddev->private = NULL wait_barrier() conf->nr_pending //trigger [1] The intervention of a stop request causes inconsistencies in the state of mddev members (such as private and pers) while a write request is executing; the mddev lock is used to synchronize write and stop requests, thereby ensuring consistent mddev state throughout the execution of the write request. Additionally, when a write operation reaches the RAID1 layer, if a stop request acquires the mddev lock first and releases mddev->private, the bio is terminated and the write request exits. [1] KASAN: null-ptr-deref in range [0x0000000000000120-0x0000000000000127] RIP: 0010:_wait_barrier+0x8d/0x700 drivers/md/raid1.c:1066 Call Trace: wait_barrier drivers/md/raid1.c:1154 [inline] raid1_write_request drivers/md/raid1.c:1506 [inline] raid1_make_request+0x484/0x31a0 drivers/md/raid1.c:1696 md_handle_request+0x824/0x1230 drivers/md/md.c:417 md_submit_bio+0x1e9/0x350 drivers/md/md.c:458 __submit_bio block/blk-core.c:681 [inline] __submit_bio+0x20e/0x3d0 block/blk-core.c:670 __submit_bio_noacct block/blk-core.c:724 [inline] submit_bio_noacct_nocheck+0x736/0xc00 block/blk-core.c:792 submit_bio_noacct+0xc93/0x2130 block/blk-core.c:925 bio_await+0x1fa/0x240 block/bio.c:1580 submit_bio_wait+0x19/0x60 block/bio.c:1598 __blkdev_direct_IO_simple+0x4cb/0x8c0 block/fops.c:98 blkdev_direct_IO+0xbee/0x2030 block/fops.c:429 blkdev_direct_write block/fops.c:699 [inline] blkdev_write_iter+0x703/0xd30 block/fops.c:767 new_sync_write fs/read_write.c:595 [inline] vfs_write+0x6af/0x1050 fs/read_write.c:687 Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Reported-by: syzbot+3fe892ea5fc292e1353f@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=3fe892ea5fc292e1353f Tested-by: syzbot+3fe892ea5fc292e1353f@syzkaller.appspotmail.com Signed-off-by: Edward Adam Davis --- drivers/md/raid1.c | 28 +++++++++++++++++++++++++++- 1 file changed, 27 insertions(+), 1 deletion(-) diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c index f0646fb24371..3b9f1fa65e65 100644 --- a/drivers/md/raid1.c +++ b/drivers/md/raid1.c @@ -1674,6 +1674,7 @@ static bool raid1_write_request(struct mddev *mddev, struct bio *bio, static bool raid1_make_request(struct mddev *mddev, struct bio *bio) { sector_t sectors; + blk_status_t status; if (unlikely(bio->bi_opf & REQ_PREFLUSH) && md_flush_request(mddev, bio)) @@ -1692,11 +1693,36 @@ static bool raid1_make_request(struct mddev *mddev, struct bio *bio) if (bio_data_dir(bio) == READ) raid1_read_request(mddev, bio, sectors, NULL); else { + int err; + md_write_start(mddev, bio); - if (!raid1_write_request(mddev, bio, sectors)) + err = mddev_lock(mddev); + + if (err < 0) { + md_write_end(mddev); + status = BLK_STS_IOERR; + goto done; + } + + if (!mddev->private) { + mddev_unlock(mddev); + md_write_end(mddev); + status = BLK_STS_OFFLINE; + goto done; + } + + err = raid1_write_request(mddev, bio, sectors); + mddev_unlock(mddev); + + if (!err) md_write_end(mddev); } +out: return true; +done: + bio->bi_status = status; + bio_endio(bio); + goto out; } static void raid1_status(struct seq_file *seq, struct mddev *mddev) -- 2.43.0