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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8D859C433EF for ; Tue, 17 May 2022 12:36:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234654AbiEQMgu (ORCPT ); Tue, 17 May 2022 08:36:50 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47168 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231401AbiEQMgt (ORCPT ); Tue, 17 May 2022 08:36:49 -0400 Received: from mail-wr1-x436.google.com (mail-wr1-x436.google.com [IPv6:2a00:1450:4864:20::436]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D48DD30F59 for ; Tue, 17 May 2022 05:36:46 -0700 (PDT) Received: by mail-wr1-x436.google.com with SMTP id h14so4917383wrc.6 for ; Tue, 17 May 2022 05:36:46 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:content-transfer-encoding:in-reply-to; bh=yh9KCD3prrmtE3wT14QIp/KiLRwsEOgLjY+dd/br9aM=; b=u05Y8niqeoVzLfYO77y8i8hMVDuTewNJJbexl4ODRci2203r1K0fKY9bvVdGOB5mn4 bVMrP0r7GneRcIBIMgJD1BTN62sLCJoi+oea9YFo/9f+Wk4USFY06kuEH3e0bBcWSvnA s5zAgVJ5eW3eI9YDtRlTRW451z/7sZcSTX7FMd0tcr8XF58BIpU+VNjFNNTu1wQKLB8R 3c7Yz9FfDQENoh9AtnPWRQNEosyPPMP2G4Bg2Il3d3N8HEvGVNvUmNVw7t8EDUjp1flv WVslgR3Bi4vqE6pZ7Nvzlkd7Ss/ZlRYMrBXaFsjiqgwKJhD+5LJo09Q723axwUxUqpPa AG5Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:content-transfer-encoding :in-reply-to; bh=yh9KCD3prrmtE3wT14QIp/KiLRwsEOgLjY+dd/br9aM=; b=1c7bxjlBTLUa5YLm0RYCvKStEyBgaeFGF3daAy3Z1OOVTeKMPq4fGfgfjYRAZFtypo 4TfyXdV6+f9w4TS0DgGyL5/eW9Jj2P3j27NZy38v5H+8pbmfA9PJ1gJKrbyve4uGPM+/ 6XHJrJYpkLGZRlSxvTMWnngO5E1KziVD6+ghepyN7j5ziqGfWZ6bCPKE+gPALAv9COO0 0lIGkUKFQGilaMazSK4zhsRqA8PklaVZvwn8mNVJuRVwMgwK7JavIuIKhLxBuirdo2bD oJ/uN/vxNj3Bl7vxr1soAjnQpENS1lXYxathrUa5NAx+NP5DjP4kXnTBMAD/6ieSw13b 3juQ== X-Gm-Message-State: AOAM530l9D0zW2vT/QuRoujMpIA3vqIy5Jo02WHM6UvtGlezb5uOprdv eWREx7EkocCO5TlcRpKTul6+OQ== X-Google-Smtp-Source: ABdhPJzKrtC8VWaJvzTf7lZpSvoGPSyOvAwojNTFmifbEtZlEYHySohWNBzK0i2sBlEfWLbMT4VAag== X-Received: by 2002:a5d:470c:0:b0:20d:135:2fb3 with SMTP id y12-20020a5d470c000000b0020d01352fb3mr12009595wrq.559.1652791005419; Tue, 17 May 2022 05:36:45 -0700 (PDT) Received: from google.com (cpc155339-bagu17-2-0-cust87.1-3.cable.virginm.net. [86.27.177.88]) by smtp.gmail.com with ESMTPSA id g2-20020adfa482000000b0020c5253d8dfsm12328385wrb.43.2022.05.17.05.36.44 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 17 May 2022 05:36:44 -0700 (PDT) Date: Tue, 17 May 2022 13:36:43 +0100 From: Lee Jones To: Jens Axboe Cc: Pavel Begunkov , io-uring@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [REPORT] Use-after-free Read in __fdget_raw in v5.10.y Message-ID: References: <97cba3e1-4ef7-0a17-8456-e0787d6702c6@kernel.dk> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org On Tue, 17 May 2022, Jens Axboe wrote: > On 5/17/22 6:24 AM, Lee Jones wrote: > > On Tue, 17 May 2022, Jens Axboe wrote: > > > >> On 5/17/22 5:41 AM, Lee Jones wrote: > >>> Good afternoon Jens, Pavel, et al., > >>> > >>> Not sure if you are presently aware, but there appears to be a > >>> use-after-free issue affecting the io_uring worker driver (fs/io-wq.c) > >>> in Stable v5.10.y. > >>> > >>> The full sysbot report can be seen below [0]. > >>> > >>> The C-reproducer has been placed below that [1]. > >>> > >>> I had great success running this reproducer in an infinite loop. > >>> > >>> My colleague reverse-bisected the fixing commit to: > >>> > >>> commit fb3a1f6c745ccd896afadf6e2d6f073e871d38ba > >>> Author: Jens Axboe > >>> Date: Fri Feb 26 09:47:20 2021 -0700 > >>> > >>> io-wq: have manager wait for all workers to exit > >>> > >>> Instead of having to wait separately on workers and manager, just have > >>> the manager wait on the workers. We use an atomic_t for the reference > >>> here, as we need to start at 0 and allow increment from that. Since the > >>> number of workers is naturally capped by the allowed nr of processes, > >>> and that uses an int, there is no risk of overflow. > >>> > >>> Signed-off-by: Jens Axboe > >>> > >>> fs/io-wq.c | 30 ++++++++++++++++++++++-------- > >>> 1 file changed, 22 insertions(+), 8 deletions(-) > >> > >> Does this fix it: > >> > >> commit 886d0137f104a440d9dfa1d16efc1db06c9a2c02 > >> Author: Jens Axboe > >> Date: Fri Mar 5 12:59:30 2021 -0700 > >> > >> io-wq: fix race in freeing 'wq' and worker access > >> > >> Looks like it didn't make it into 5.10-stable, but we can certainly > >> rectify that. > > > > Thanks for your quick response Jens. > > > > This patch doesn't apply cleanly to v5.10.y. > > This is probably why it never made it into 5.10-stable :-/ Right. It doesn't apply at all unfortunately. > > I'll have a go at back-porting it. Please bear with me. > > Let me know if you into issues with that and I can help out. I think the dependency list is too big. Too much has changed that was never back-ported. Actually the list of patches pertaining to fs/io-wq.c alone isn't so bad, I did start to back-port them all but some of the big ones have fs/io_uring.c changes incorporated and that list is huge (256 patches from v5.10 to the fixing patch mentioned above). -- Lee Jones [李琼斯] Principal Technical Lead - Developer Services Linaro.org │ Open source software for Arm SoCs Follow Linaro: Facebook | Twitter | Blog