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Thu, 16 Dec 2021 09:02:58 -0800 (PST) Received: from google.com ([2.31.167.18]) by smtp.gmail.com with ESMTPSA id b132sm5251570wmd.38.2021.12.16.09.02.54 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 16 Dec 2021 09:02:57 -0800 (PST) Date: Thu, 16 Dec 2021 17:02:52 +0000 From: Lee Jones To: Pavel Begunkov Cc: Jens Axboe , syzbot , io-uring@vger.kernel.org, linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com, Greg Kroah-Hartman Subject: Re: [syzbot] KASAN: stack-out-of-bounds Read in iov_iter_revert Message-ID: References: <6f7d4c1d-f923-3ab1-c525-45316b973c72@gmail.com> <00000000000047f3b805c962affb@google.com> <0b4a5ff8-12e5-3cc7-8971-49e576444c9a@gmail.com> 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: linux-kernel@vger.kernel.org On Wed, 15 Dec 2021, Pavel Begunkov wrote: > On 12/15/21 08:06, Lee Jones wrote: > > On Tue, 09 Nov 2021, Lee Jones wrote: > > > > > On Mon, 08 Nov 2021, Jens Axboe wrote: > > > > On 11/8/21 8:29 AM, Pavel Begunkov wrote: > > > > > On 11/3/21 17:01, Lee Jones wrote: > > > > > > Good afternoon Pavel, > > > > > > > > > > > > > syzbot has tested the proposed patch and the reproducer did not trigger any issue: > > > > > > > > > > > > > > Reported-and-tested-by: syzbot+9671693590ef5aad8953@syzkaller.appspotmail.com > > > > > > > > > > > > > > Tested on: > > > > > > > > > > > > > > commit: bff2c168 io_uring: don't retry with truncated iter > > > > > > > git tree: https://github.com/isilence/linux.git truncate > > > > > > > kernel config: https://syzkaller.appspot.com/x/.config?x=730106bfb5bf8ace > > > > > > > dashboard link: https://syzkaller.appspot.com/bug?extid=9671693590ef5aad8953 > > > > > > > compiler: Debian clang version 11.0.1-2, GNU ld (GNU Binutils for Debian) 2.35.1 > > > > > > > > > > > > > > Note: testing is done by a robot and is best-effort only. > > > > > > > > > > > > As you can see in the 'dashboard link' above this bug also affects > > > > > > android-5-10 which is currently based on v5.10.75. > > > > > > > > > > > > I see that the back-port of this patch failed in v5.10.y: > > > > > > > > > > > > https://lore.kernel.org/stable/163152589512611@kroah.com/ > > > > > > > > > > > > And after solving the build-error by back-porting both: > > > > > > > > > > > > 2112ff5ce0c11 iov_iter: track truncated size > > > > > > 89c2b3b749182 io_uring: reexpand under-reexpanded iters > > > > > > > > > > > > I now see execution tripping the WARN() in iov_iter_revert(): > > > > > > > > > > > > if (WARN_ON(unroll > MAX_RW_COUNT)) > > > > > > return > > > > > > > > > > > > Am I missing any additional patches required to fix stable/v5.10.y? > > > > > > > > > > Is it the same syz test? There was a couple more patches for > > > > > IORING_SETUP_IOPOLL, but strange if that's not the case. > > > > > > > > > > > > > > > fwiw, Jens decided to replace it with another mechanism shortly > > > > > after, so it may be a better idea to backport those. Jens, > > > > > what do you think? > > > > > > > > > > > > > > > commit 8fb0f47a9d7acf620d0fd97831b69da9bc5e22ed > > > > > Author: Jens Axboe > > > > > Date: Fri Sep 10 11:18:36 2021 -0600 > > > > > > > > > > iov_iter: add helper to save iov_iter state > > > > > > > > > > commit cd65869512ab5668a5d16f789bc4da1319c435c4 > > > > > Author: Jens Axboe > > > > > Date: Fri Sep 10 11:19:14 2021 -0600 > > > > > > > > > > io_uring: use iov_iter state save/restore helpers > > > > > > > > Yes, I think backporting based on the save/restore setup is the > > > > sanest way by far. > > > > > > Would you be kind enough to attempt to send these patches to Stable? > > > > > > When I tried to back-port them, the second one gave me trouble. And > > > without the in depth knowledge of the driver/subsystem that you guys > > > have, I found it almost impossible to resolve all of the conflicts: > > > > Any movement on this chaps? > > > > Not sure I am able to do this back-port without your help. > > Apologies, slipped from my attention, we'll backport it, > and thanks for the reminder Excellent. Thanks Pavel. -- Lee Jones [李琼斯] Senior Technical Lead - Developer Services Linaro.org │ Open source software for Arm SoCs Follow Linaro: Facebook | Twitter | Blog