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=-9.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,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 CAF23FA372C for ; Fri, 8 Nov 2019 19:12:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9C94C20650 for ; Fri, 8 Nov 2019 19:12:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1573240325; bh=kzrBvDn8b+xm6hOzUrZqUhVGdPdFyZ3bEpJWX+vn26g=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=esqf9J0NUUzUclEa2GYVB8IA4J4DshLgvqbSaVTFq/DkxQKJcXGdkPgFLslZzeZbj xminWgQF0s9bt0Wgl5Y8nF83HoVPn9oOcyUZImyIjLcP/E2X6/L5d+/0tqqxT+zXtx 7hqaC5TBcpcqfZWIBeoroYsu/OXTqalrLAdLRh+g= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2391035AbfKHTME (ORCPT ); Fri, 8 Nov 2019 14:12:04 -0500 Received: from mail.kernel.org ([198.145.29.99]:41808 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2391164AbfKHTJy (ORCPT ); Fri, 8 Nov 2019 14:09:54 -0500 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id A2029206A3; Fri, 8 Nov 2019 19:09:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1573240192; bh=kzrBvDn8b+xm6hOzUrZqUhVGdPdFyZ3bEpJWX+vn26g=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Qsx0ECXZqxv7MzBkOMAFMLkNieEefNjm2Jm0I7qKy/+k3qrOy3ZhHv7u/fbx1Qq8I 9GPna6Qp/ypIJoUh7/QwBUzVGUrGMFhda9CWOBlIgQ8oSzdkxVIf7pJ3XCvFkMkiT0 SWSRmVtBORF5eGdT0TlixfpH26ul+gLiMfpopkPQ= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Mike Christie , Josef Bacik , Jens Axboe , Sasha Levin Subject: [PATCH 5.3 078/140] nbd: handle racing with errored out commands Date: Fri, 8 Nov 2019 19:50:06 +0100 Message-Id: <20191108174910.037122962@linuxfoundation.org> X-Mailer: git-send-email 2.24.0 In-Reply-To: <20191108174900.189064908@linuxfoundation.org> References: <20191108174900.189064908@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Josef Bacik [ Upstream commit 7ce23e8e0a9cd38338fc8316ac5772666b565ca9 ] We hit the following warning in production print_req_error: I/O error, dev nbd0, sector 7213934408 flags 80700 ------------[ cut here ]------------ refcount_t: underflow; use-after-free. WARNING: CPU: 25 PID: 32407 at lib/refcount.c:190 refcount_sub_and_test_checked+0x53/0x60 Workqueue: knbd-recv recv_work [nbd] RIP: 0010:refcount_sub_and_test_checked+0x53/0x60 Call Trace: blk_mq_free_request+0xb7/0xf0 blk_mq_complete_request+0x62/0xf0 recv_work+0x29/0xa1 [nbd] process_one_work+0x1f5/0x3f0 worker_thread+0x2d/0x3d0 ? rescuer_thread+0x340/0x340 kthread+0x111/0x130 ? kthread_create_on_node+0x60/0x60 ret_from_fork+0x1f/0x30 ---[ end trace b079c3c67f98bb7c ]--- This was preceded by us timing out everything and shutting down the sockets for the device. The problem is we had a request in the queue at the same time, so we completed the request twice. This can actually happen in a lot of cases, we fail to get a ref on our config, we only have one connection and just error out the command, etc. Fix this by checking cmd->status in nbd_read_stat. We only change this under the cmd->lock, so we are safe to check this here and see if we've already error'ed this command out, which would indicate that we've completed it as well. Reviewed-by: Mike Christie Signed-off-by: Josef Bacik Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin --- drivers/block/nbd.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c index 7301fe55084bf..5f9d12ce91e5a 100644 --- a/drivers/block/nbd.c +++ b/drivers/block/nbd.c @@ -673,6 +673,12 @@ static struct nbd_cmd *nbd_read_stat(struct nbd_device *nbd, int index) ret = -ENOENT; goto out; } + if (cmd->status != BLK_STS_OK) { + dev_err(disk_to_dev(nbd->disk), "Command already handled %p\n", + req); + ret = -ENOENT; + goto out; + } if (test_bit(NBD_CMD_REQUEUED, &cmd->flags)) { dev_err(disk_to_dev(nbd->disk), "Raced with timeout on req %p\n", req); -- 2.20.1