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 Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 06919C4332F for ; Mon, 21 Nov 2022 22:23:18 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1oxFBe-00063Q-Kc; Mon, 21 Nov 2022 17:22:46 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1oxFBZ-0005y7-Ka for qemu-devel@nongnu.org; Mon, 21 Nov 2022 17:22:43 -0500 Received: from mail-wm1-x331.google.com ([2a00:1450:4864:20::331]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1oxFBV-00014f-UF for qemu-devel@nongnu.org; Mon, 21 Nov 2022 17:22:41 -0500 Received: by mail-wm1-x331.google.com with SMTP id 84-20020a1c0257000000b003cfe48519a6so7640803wmc.0 for ; Mon, 21 Nov 2022 14:22:36 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=content-transfer-encoding:in-reply-to:from:references:cc:to :content-language:subject:user-agent:mime-version:date:message-id :from:to:cc:subject:date:message-id:reply-to; bh=A2j3GmXuI9XKAIWRsHodPvBvsO03adz3Gz2KpYT2070=; b=j7tB85iClHpVb6MXAyKxLf7jaC7Am0xNiJjLaSHtT7Pvg6xoRmDwnM+z5fi4CtlXeF tBiFqia6SR+8J61r2hb+h37JEsd5yIXg/uEflJdumwr3D2vfRu900TMIXsYnXA7STaAe NpmmJ/oraXmQTUyH3x7FTWy+zdjWV+VpT5hBkw/94aVZkbZgbZ/JWcZYuhYxN+xbE4gJ swM9+zz1UayVuEOZJ5pfOAqRVURh0jb2pJ0klwqyjV0dFtnWPUndRJgoPjkT/Fc15yss bI4N9YrS1jwOHy8DTaU4KE6fN24hLkQq046Bv7+IZzFa1n8fZ6LvlNk+aQjPOHJrwlxb gjyw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:in-reply-to:from:references:cc:to :content-language:subject:user-agent:mime-version:date:message-id :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=A2j3GmXuI9XKAIWRsHodPvBvsO03adz3Gz2KpYT2070=; b=d50AKV+RmCl7MhX9GZH3rby2ymOCqnc8VkGQvho2ZLXzf71kcY3vrQKICby5EqsyOD wLAV3yYVEYL525EISu1aUwPpwmaXdf4p4G0XYhe2pvhGkG3p/GK+TUBrd8Bq6eW40K3Y aNVYXvLuCzLE40cNp5vQQsCnXkPq6AtWVe6acy1a7bOeLe10T/pKSPVkAQQ92bamB8LO 9OU7CNdnHh47Y1UUGjuZxnznfXDYgqi8DLr0aXtCAXrWcVBmOyT+YrJkgFTvunVXiCsE +wijCMHba56WJwGWwhYpXv66mcLe+5XWcHsQTO4Ex60MKCTUlsITLPChA7NjRULDkDLX Q1Mw== X-Gm-Message-State: ANoB5pldTTFlI2yR91oPgqzMh+CTYvR4GBFy/fiffQUBiZV3Xt22HZlQ lafm1yHkRBQgGz/RI7/b+umNyQ== X-Google-Smtp-Source: AA0mqf7BFDbAFIzXFf9V8TXl6qfr29VKWGjZxfmxdtBa64V570SLPXHSzMpCLtmxGNzACg+9FGk5uA== X-Received: by 2002:a05:600c:21d2:b0:3cf:b2b1:3c7 with SMTP id x18-20020a05600c21d200b003cfb2b103c7mr1062704wmj.176.1669069354899; Mon, 21 Nov 2022 14:22:34 -0800 (PST) Received: from [192.168.1.115] ([185.126.107.38]) by smtp.gmail.com with ESMTPSA id h3-20020a05600c2ca300b003b49bd61b19sm19826566wmc.15.2022.11.21.14.22.33 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 21 Nov 2022 14:22:34 -0800 (PST) Message-ID: <18e94ec0-6f79-8e7b-8a97-6d1824f83033@linaro.org> Date: Mon, 21 Nov 2022 23:22:33 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:102.0) Gecko/20100101 Thunderbird/102.5.0 Subject: Re: [PATCH for-7.2] block-backend: avoid bdrv_unregister_buf() NULL pointer deref Content-Language: en-US To: Stefan Hajnoczi , qemu-devel@nongnu.org Cc: qemu-block@nongnu.org, Hanna Reitz , Kevin Wolf , Jonathan Cameron References: <20221121211923.1993171-1-stefanha@redhat.com> From: =?UTF-8?Q?Philippe_Mathieu-Daud=c3=a9?= In-Reply-To: <20221121211923.1993171-1-stefanha@redhat.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=2a00:1450:4864:20::331; envelope-from=philmd@linaro.org; helo=mail-wm1-x331.google.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, NICE_REPLY_A=-0.001, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On 21/11/22 22:19, Stefan Hajnoczi wrote: > bdrv_*() APIs expect a valid BlockDriverState. Calling them with bs=NULL > leads to undefined behavior. > > Jonathan Cameron reported this following NULL pointer dereference when a > VM with a virtio-blk device and a memory-backend-file object is > terminated: > 1. qemu_cleanup() closes all drives, setting blk->root to NULL > 2. qemu_cleanup() calls user_creatable_cleanup(), which results in a RAM > block notifier callback because the memory-backend-file is destroyed. > 3. blk_unregister_buf() is called by virtio-blk's BlockRamRegistrar > notifier callback and undefined behavior occurs. > > Fixes: baf422684d73 ("virtio-blk: use BDRV_REQ_REGISTERED_BUF optimization hint") > Co-authored-by: Jonathan Cameron > Signed-off-by: Stefan Hajnoczi > --- > block/block-backend.c | 15 +++++++++++++-- > 1 file changed, 13 insertions(+), 2 deletions(-) Reviewed-by: Philippe Mathieu-Daudé