From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-18.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_RED, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 43A9FC433E9 for ; Mon, 28 Dec 2020 13:42:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 15E902072C for ; Mon, 28 Dec 2020 13:42:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2404240AbgL1Nmf (ORCPT ); Mon, 28 Dec 2020 08:42:35 -0500 Received: from mail.kernel.org ([198.145.29.99]:42802 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2404165AbgL1Nmb (ORCPT ); Mon, 28 Dec 2020 08:42:31 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id F027822583; Mon, 28 Dec 2020 13:41:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1609162910; bh=479dHjWVBqTckJTd0L+TxRhECBYiBNzTxXs3CzEHzDE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Hq4k4dFXkIntNEWuWyJDGw+lqyCjTByA4SPi8l/hKV7qqK+Z5TnD25jrN9LOeDmQX qMeMKQlB5TQnA24nA3tbyHi4ENAyqGK295+YHxjvCq+KnLeAimKbAGBmLwsdpz0JCY 9dAjmm9f90ueE0tYIpUHP8rkyguAXV78AKvvSaVE= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, syzbot+1e46a0864c1a6e9bd3d8@syzkaller.appspotmail.com, "Dae R. Jeong" , Song Liu Subject: [PATCH 5.4 072/453] md: fix a warning caused by a race between concurrent md_ioctl()s Date: Mon, 28 Dec 2020 13:45:08 +0100 Message-Id: <20201228124940.713291212@linuxfoundation.org> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20201228124937.240114599@linuxfoundation.org> References: <20201228124937.240114599@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Dae R. Jeong commit c731b84b51bf7fe83448bea8f56a6d55006b0615 upstream. Syzkaller reports a warning as belows. WARNING: CPU: 0 PID: 9647 at drivers/md/md.c:7169 ... Call Trace: ... RIP: 0010:md_ioctl+0x4017/0x5980 drivers/md/md.c:7169 RSP: 0018:ffff888096027950 EFLAGS: 00010293 RAX: ffff88809322c380 RBX: 0000000000000932 RCX: ffffffff84e266f2 RDX: 0000000000000000 RSI: ffffffff84e299f7 RDI: 0000000000000007 RBP: ffff888096027bc0 R08: ffff88809322c380 R09: ffffed101341a482 R10: ffff888096027940 R11: ffff88809a0d240f R12: 0000000000000932 R13: ffff8880a2c14100 R14: ffff88809a0d2268 R15: ffff88809a0d2408 __blkdev_driver_ioctl block/ioctl.c:304 [inline] blkdev_ioctl+0xece/0x1c10 block/ioctl.c:606 block_ioctl+0xee/0x130 fs/block_dev.c:1930 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:509 [inline] do_vfs_ioctl+0xd5f/0x1380 fs/ioctl.c:696 ksys_ioctl+0xab/0xd0 fs/ioctl.c:713 __do_sys_ioctl fs/ioctl.c:720 [inline] __se_sys_ioctl fs/ioctl.c:718 [inline] __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:718 do_syscall_64+0xfd/0x680 arch/x86/entry/common.c:301 entry_SYSCALL_64_after_hwframe+0x49/0xbe This is caused by a race between two concurrenct md_ioctl()s closing the array. CPU1 (md_ioctl()) CPU2 (md_ioctl()) ------ ------ set_bit(MD_CLOSING, &mddev->flags); did_set_md_closing = true; WARN_ON_ONCE(test_bit(MD_CLOSING, &mddev->flags)); if(did_set_md_closing) clear_bit(MD_CLOSING, &mddev->flags); Fix the warning by returning immediately if the MD_CLOSING bit is set in &mddev->flags which indicates that the array is being closed. Fixes: 065e519e71b2 ("md: MD_CLOSING needs to be cleared after called md_set_readonly or do_md_stop") Reported-by: syzbot+1e46a0864c1a6e9bd3d8@syzkaller.appspotmail.com Cc: stable@vger.kernel.org Signed-off-by: Dae R. Jeong Signed-off-by: Song Liu Signed-off-by: Greg Kroah-Hartman --- drivers/md/md.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -7371,8 +7371,11 @@ static int md_ioctl(struct block_device err = -EBUSY; goto out; } - WARN_ON_ONCE(test_bit(MD_CLOSING, &mddev->flags)); - set_bit(MD_CLOSING, &mddev->flags); + if (test_and_set_bit(MD_CLOSING, &mddev->flags)) { + mutex_unlock(&mddev->open_mutex); + err = -EBUSY; + goto out; + } did_set_md_closing = true; mutex_unlock(&mddev->open_mutex); sync_blockdev(bdev);