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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B39AFC433EF for ; Fri, 24 Sep 2021 17:06:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8066460EE9 for ; Fri, 24 Sep 2021 17:06:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1343568AbhIXRIG (ORCPT ); Fri, 24 Sep 2021 13:08:06 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46654 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S245679AbhIXRIF (ORCPT ); Fri, 24 Sep 2021 13:08:05 -0400 Received: from mail-io1-xd29.google.com (mail-io1-xd29.google.com [IPv6:2607:f8b0:4864:20::d29]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B7737C061613 for ; Fri, 24 Sep 2021 10:06:31 -0700 (PDT) Received: by mail-io1-xd29.google.com with SMTP id q205so13534993iod.8 for ; Fri, 24 Sep 2021 10:06:31 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel-dk.20210112.gappssmtp.com; s=20210112; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=buBo8TkuaLnLPT4SKYQyAEPp/d82uwvxJ08uqCLKYxs=; b=VusRO3SQ3l/meRDKcOPMceqMsV9IFMcMIgUGCD6OI/F1KAUqvKh6tsPwyxSsQdFcEl G6eA4zfuYr3ex6+u983e/s7JJJq1Qi681HLd6sRFTf+Ncf6/nq/ZrCY7eIt//4KKBFH4 VnwKYryuAsUXkBaWTzh1i67/NKDtMZjp2TYSx/h3qaCDfZXIecwyoGAOC1eK/+J4cbMV I+L8eU2KD0otVtyt197ZECiZWT1N4hC72AhmSA/NGxCr/8/BZQcInIfbeLIcilTgye1Q ohPeIPpxqYdw8+sJ5prZ8m6YPGFX5rIItWjgeXZAnIlU6ozx2zxe+96E9pEpwlgEI1mW aTrw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=buBo8TkuaLnLPT4SKYQyAEPp/d82uwvxJ08uqCLKYxs=; b=inZk3LRYKWqSyWAPb8bp3f8OPUBrH5OOazW3JNld5OM4Ws0A/FWwJXRdBUHQ2T3zxW vd41VcVdA788d3eXYNufkBzGD08tk6QwxcM8rYy6QLP5/Wj/EHZj1iLY29tpCT7pvC2S e22ILdMyvIgkRCqwajGX9Up/rVmbi3tkCcz9qf1aWcZhxeSFHXgiA15+ARrjwDcz3b+R ykuATKKUJvQFzaXZDYsyh/+mvwmDok9zuahHTC0+gt4u26EiAQRIEDfB18ji4TinuRKq aNcSr3Fe5xOZWCnrwH7RzXQGi/fDIe8jwBOgwqULpSDgwWnIwsNDbuVvueUQQyFlmivc tsTQ== X-Gm-Message-State: AOAM532Hdm8l+lBge8mzotm0lPZIBNq98gt3GVvTZntVHx1EbcwvcqE6 u24oJX7/nh1MWdv9zyzFOw8zigM86SUQR/gAbG4= X-Google-Smtp-Source: ABdhPJwQkM2Qt7xUqyEbgcEHGyfAfH/e+2mZ3jPF4JYiKqa6jd24jcP/mHcej8E9D9QtxggAshmmGA== X-Received: by 2002:a02:1049:: with SMTP id 70mr10341263jay.123.1632503190795; Fri, 24 Sep 2021 10:06:30 -0700 (PDT) Received: from [192.168.1.30] ([207.135.234.126]) by smtp.gmail.com with ESMTPSA id h11sm4544943ilc.7.2021.09.24.10.06.30 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 24 Sep 2021 10:06:30 -0700 (PDT) Subject: Re: [PATCH v2] blktrace: Fix uaf in blk_trace access after removing by sysfs To: Zhihao Cheng , rostedt@goodmis.org, mingo@redhat.com, acme@redhat.com, hch@infradead.org Cc: linux-block@vger.kernel.org, linux-kernel@vger.kernel.org References: <20210923134921.109194-1-chengzhihao1@huawei.com> From: Jens Axboe Message-ID: Date: Fri, 24 Sep 2021 11:06:29 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <20210923134921.109194-1-chengzhihao1@huawei.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 9/23/21 7:49 AM, Zhihao Cheng wrote: > There is an use-after-free problem triggered by following process: > > P1(sda) P2(sdb) > echo 0 > /sys/block/sdb/trace/enable > blk_trace_remove_queue > synchronize_rcu > blk_trace_free > relay_close > rcu_read_lock > __blk_add_trace > trace_note_tsk > (Iterate running_trace_list) > relay_close_buf > relay_destroy_buf > kfree(buf) > trace_note(sdb's bt) > relay_reserve > buf->offset <- nullptr deference (use-after-free) !!! > rcu_read_unlock > > [ 502.714379] BUG: kernel NULL pointer dereference, address: > 0000000000000010 > [ 502.715260] #PF: supervisor read access in kernel mode > [ 502.715903] #PF: error_code(0x0000) - not-present page > [ 502.716546] PGD 103984067 P4D 103984067 PUD 17592b067 PMD 0 > [ 502.717252] Oops: 0000 [#1] SMP > [ 502.720308] RIP: 0010:trace_note.isra.0+0x86/0x360 > [ 502.732872] Call Trace: > [ 502.733193] __blk_add_trace.cold+0x137/0x1a3 > [ 502.733734] blk_add_trace_rq+0x7b/0xd0 > [ 502.734207] blk_add_trace_rq_issue+0x54/0xa0 > [ 502.734755] blk_mq_start_request+0xde/0x1b0 > [ 502.735287] scsi_queue_rq+0x528/0x1140 > ... > [ 502.742704] sg_new_write.isra.0+0x16e/0x3e0 > [ 502.747501] sg_ioctl+0x466/0x1100 > > Reproduce method: > ioctl(/dev/sda, BLKTRACESETUP, blk_user_trace_setup[buf_size=127]) > ioctl(/dev/sda, BLKTRACESTART) > ioctl(/dev/sdb, BLKTRACESETUP, blk_user_trace_setup[buf_size=127]) > ioctl(/dev/sdb, BLKTRACESTART) > > echo 0 > /sys/block/sdb/trace/enable & > // Add delay(mdelay/msleep) before kernel enters blk_trace_free() > > ioctl$SG_IO(/dev/sda, SG_IO, ...) > // Enters trace_note_tsk() after blk_trace_free() returned > // Use mdelay in rcu region rather than msleep(which may schedule out) > > Remove blk_trace from running_list before calling blk_trace_free() by > sysfs if blk_trace is at Blktrace_running state. Applied, thanks. -- Jens Axboe