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=-10.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING, NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 05234C433E6 for ; Fri, 12 Mar 2021 13:50:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BACDB64F9E for ; Fri, 12 Mar 2021 13:50:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231496AbhCLNuP (ORCPT ); Fri, 12 Mar 2021 08:50:15 -0500 Received: from imap3.hz.codethink.co.uk ([176.9.8.87]:44926 "EHLO imap3.hz.codethink.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229995AbhCLNuK (ORCPT ); Fri, 12 Mar 2021 08:50:10 -0500 Received: from cpc79921-stkp12-2-0-cust288.10-2.cable.virginm.net ([86.16.139.33] helo=[192.168.0.18]) by imap3.hz.codethink.co.uk with esmtpsa (Exim 4.92 #3 (Debian)) id 1lKiAt-0008V6-CR; Fri, 12 Mar 2021 13:49:55 +0000 Subject: Re: [syzbot] BUG: unable to handle kernel access to user memory in schedule_tail To: Dmitry Vyukov , syzbot , Paul Walmsley , Palmer Dabbelt , Albert Ou , linux-riscv Cc: Daniel Bristot de Oliveira , Benjamin Segall , dietmar.eggemann@arm.com, Juri Lelli , LKML , Mel Gorman , Ingo Molnar , Peter Zijlstra , Steven Rostedt , syzkaller-bugs , Vincent Guittot References: <000000000000b74f1b05bd316729@google.com> From: Ben Dooks Organization: Codethink Limited. Message-ID: <84b0471d-42c1-175f-ae1d-a18c310c7f77@codethink.co.uk> Date: Fri, 12 Mar 2021 13:49:53 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.8.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-GB Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10/03/2021 17:16, Dmitry Vyukov wrote: > On Wed, Mar 10, 2021 at 5:46 PM syzbot > wrote: >> >> Hello, >> >> syzbot found the following issue on: >> >> HEAD commit: 0d7588ab riscv: process: Fix no prototype for arch_dup_tas.. >> git tree: git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux.git fixes >> console output: https://syzkaller.appspot.com/x/log.txt?x=1212c6e6d00000 >> kernel config: https://syzkaller.appspot.com/x/.config?x=e3c595255fb2d136 >> dashboard link: https://syzkaller.appspot.com/bug?extid=e74b94fe601ab9552d69 >> userspace arch: riscv64 >> >> Unfortunately, I don't have any reproducer for this issue yet. >> >> IMPORTANT: if you fix the issue, please add the following tag to the commit: >> Reported-by: syzbot+e74b94fe601ab9552d69@syzkaller.appspotmail.com > > +riscv maintainers > > This is riscv64-specific. > I've seen similar crashes in put_user in other places. It looks like > put_user crashes in the user address is not mapped/protected (?). I've been having a look, and this seems to be down to access of the tsk->set_child_tid variable. I assume the fuzzing here is to pass a bad address to clone? From looking at the code, the put_user() code should have set the relevant SR_SUM bit (the value for this, which is 1<<18 is in the s2 register in the crash report) and from looking at the compiler output from my gcc-10, the code looks to be dong the relevant csrs and then csrc around the put_user So currently I do not understand how the above could have happened over than something re-tried the code seqeunce and ended up retrying the faulting instruction without the SR_SUM bit set. -- Ben Dooks http://www.codethink.co.uk/ Senior Engineer Codethink - Providing Genius https://www.codethink.co.uk/privacy.html 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=-10.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 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 5CE4EC433E0 for ; Fri, 12 Mar 2021 13:50:36 +0000 (UTC) Received: from desiato.infradead.org (desiato.infradead.org [90.155.92.199]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id C98E764F9E for ; Fri, 12 Mar 2021 13:50:35 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C98E764F9E Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=codethink.co.uk Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=desiato.20200630; h=Sender:Content-Type: Content-Transfer-Encoding:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:Date:Message-ID:From: References:Cc:To:Subject:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=XXN5MEVVIGzAzOwDcWaPTMqB3VM7BTi9CwDMxsEVQnA=; b=ToppjuKuryHjPSdGhaZMzSVf7 vJWq1MXMR//inwrHZCsa+I5+PJuo3DOc+VQKUBmGi9+50moNSFTP59746e6QotcwCvq0vwj+3q7WH EvgZCYA60+h3zZj6b3ZprurIjkCXo1GshMKQWL3MCFQKVe0bB/xZN02xVVlgYWcodrsyKYXDIKP4L TxxX631K+/8tU6ctxVAP0BtmxJaj29Kp0ZqUIiuA6VXIE5rKX2N1wYQ0VHYNgdzljtzbZVuO73Om7 vdXsAaOJitPBGTHvYgP/O4DB6x45ySjurKREqZ2BidUJ/CoIjtdGIkmJ91soOM7ddvtgYnraZE9wv kzrxk3yOQ==; Received: from localhost ([::1] helo=desiato.infradead.org) by desiato.infradead.org with esmtp (Exim 4.94 #2 (Red Hat Linux)) id 1lKiBJ-00BYnK-Vi; Fri, 12 Mar 2021 13:50:22 +0000 Received: from imap3.hz.codethink.co.uk ([176.9.8.87]) by desiato.infradead.org with esmtps (Exim 4.94 #2 (Red Hat Linux)) id 1lKiBD-00BYmD-BB for linux-riscv@lists.infradead.org; Fri, 12 Mar 2021 13:50:19 +0000 Received: from cpc79921-stkp12-2-0-cust288.10-2.cable.virginm.net ([86.16.139.33] helo=[192.168.0.18]) by imap3.hz.codethink.co.uk with esmtpsa (Exim 4.92 #3 (Debian)) id 1lKiAt-0008V6-CR; Fri, 12 Mar 2021 13:49:55 +0000 Subject: Re: [syzbot] BUG: unable to handle kernel access to user memory in schedule_tail To: Dmitry Vyukov , syzbot , Paul Walmsley , Palmer Dabbelt , Albert Ou , linux-riscv Cc: Daniel Bristot de Oliveira , Benjamin Segall , dietmar.eggemann@arm.com, Juri Lelli , LKML , Mel Gorman , Ingo Molnar , Peter Zijlstra , Steven Rostedt , syzkaller-bugs , Vincent Guittot References: <000000000000b74f1b05bd316729@google.com> From: Ben Dooks Organization: Codethink Limited. Message-ID: <84b0471d-42c1-175f-ae1d-a18c310c7f77@codethink.co.uk> Date: Fri, 12 Mar 2021 13:49:53 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.8.0 MIME-Version: 1.0 In-Reply-To: Content-Language: en-GB X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210312_135017_041276_DE8C4AE7 X-CRM114-Status: GOOD ( 18.57 ) X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "linux-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org On 10/03/2021 17:16, Dmitry Vyukov wrote: > On Wed, Mar 10, 2021 at 5:46 PM syzbot > wrote: >> >> Hello, >> >> syzbot found the following issue on: >> >> HEAD commit: 0d7588ab riscv: process: Fix no prototype for arch_dup_tas.. >> git tree: git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux.git fixes >> console output: https://syzkaller.appspot.com/x/log.txt?x=1212c6e6d00000 >> kernel config: https://syzkaller.appspot.com/x/.config?x=e3c595255fb2d136 >> dashboard link: https://syzkaller.appspot.com/bug?extid=e74b94fe601ab9552d69 >> userspace arch: riscv64 >> >> Unfortunately, I don't have any reproducer for this issue yet. >> >> IMPORTANT: if you fix the issue, please add the following tag to the commit: >> Reported-by: syzbot+e74b94fe601ab9552d69@syzkaller.appspotmail.com > > +riscv maintainers > > This is riscv64-specific. > I've seen similar crashes in put_user in other places. It looks like > put_user crashes in the user address is not mapped/protected (?). I've been having a look, and this seems to be down to access of the tsk->set_child_tid variable. I assume the fuzzing here is to pass a bad address to clone? From looking at the code, the put_user() code should have set the relevant SR_SUM bit (the value for this, which is 1<<18 is in the s2 register in the crash report) and from looking at the compiler output from my gcc-10, the code looks to be dong the relevant csrs and then csrc around the put_user So currently I do not understand how the above could have happened over than something re-tried the code seqeunce and ended up retrying the faulting instruction without the SR_SUM bit set. -- Ben Dooks http://www.codethink.co.uk/ Senior Engineer Codethink - Providing Genius https://www.codethink.co.uk/privacy.html _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv