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a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=mdl713s/21KiGyh/DTXFNyf+tvozyDwj9ae9RDlS6aw=; b=CIry7uJEeA4b1WXF+UGCn83khxJJo1ySz+8M438NU8urtX1IfN1y80pzWyXy3ubx67 chuEBw2Us6prCEC7oBcuZJPgeu4iiFBcgsxpKVKx8bPL1yr19eFKeQRfcv88B3cNsP1x qNjKrPH8xKtQhx1vDCaHzJ6p3wqjzbveWhEpNortUvM0grJV8y9J4gCAIEwz+tXLjhyB pjNIhj0FKL39hJLbns5vnyxWxVGv219NU43/IsYPr77y68bDOHlPN57BG58+auuWzOhV UFMyhY9MRp3zB0ZSVUZqVvk+ybkYZSfC4zMBla3RuUZ8cjmMKcxd9cSWMKsCLuP1074z shGg== X-Gm-Message-State: AOAM531zcCCnFW8bJqbBlOjl2b6hffyi8lmJUGRtYMwGTOX0vtvU1k3W EY7TFabJcVQ0rPZoPGo7zHN/b5YI8sO5pOiSX1RcCA== X-Google-Smtp-Source: ABdhPJzudV+I630n1SVMaDIVN8XccwXytfWIVGc1y9T7v8EfrFOLYIK7l1kvgw2YoJ5d7EorNZFaJwSFzSBQJ0XZeJc= X-Received: by 2002:ac8:66c9:: with SMTP id m9mr422359qtp.43.1611773826679; Wed, 27 Jan 2021 10:57:06 -0800 (PST) MIME-Version: 1.0 References: <0000000000009bbb7905b9e4a624@google.com> <20210127171453.GC358@willie-the-truck> In-Reply-To: From: Dmitry Vyukov Date: Wed, 27 Jan 2021 19:56:55 +0100 Message-ID: Subject: Re: WARNING in __do_kernel_fault To: Andrey Konovalov X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210127_135709_037465_75637726 X-CRM114-Status: GOOD ( 28.21 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , syzbot , Catalin Marinas , syzkaller-bugs , LKML , Will Deacon , Dave Martin , Linux ARM Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Wed, Jan 27, 2021 at 7:46 PM 'Andrey Konovalov' via syzkaller-bugs wrote: > > On Wed, Jan 27, 2021 at 6:24 PM Dmitry Vyukov wrote: > > > > On Wed, Jan 27, 2021 at 6:15 PM Will Deacon wrote: > > > > > > On Wed, Jan 27, 2021 at 06:00:30PM +0100, Dmitry Vyukov wrote: > > > > On Wed, Jan 27, 2021 at 5:56 PM syzbot > > > > wrote: > > > > > > > > > > Hello, > > > > > > > > > > syzbot found the following issue on: > > > > > > > > > > HEAD commit: 2ab38c17 mailmap: remove the "repo-abbrev" comment > > > > > git tree: upstream > > > > > console output: https://syzkaller.appspot.com/x/log.txt?x=15a25264d00000 > > > > > kernel config: https://syzkaller.appspot.com/x/.config?x=ad43be24faf1194c > > > > > dashboard link: https://syzkaller.appspot.com/bug?extid=45b6fce29ff97069e2c5 > > > > > userspace arch: arm64 > > > > > > > > > > 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+45b6fce29ff97069e2c5@syzkaller.appspotmail.com > > > > > > > > This happens on arm64 instance with mte enabled. > > > > There is a GPF in reiserfs_xattr_init on x86_64 reported: > > > > https://syzkaller.appspot.com/bug?id=8abaedbdeb32c861dc5340544284167dd0e46cde > > > > so I would assume it's just a plain NULL deref. Is this WARNING not > > > > indicative of a kernel bug? Or there is something special about this > > > > particular NULL deref? > > > > > > Congratulations, you're the first person to trigger this warning! > > > > > > This fires if we take an unexpected data abort in the kernel but when we > > > get into the fault handler the page-table looks ok (according to the CPU via > > > an 'AT' instruction). Are you using QEMU system emulation? Perhaps its > > > handling of AT isn't quite right. > > > > Hi Will, > > > > Yes, it's qemu-system-aarch64 5.2 with -machine virt,mte=on -cpu max. > > Do you see any way forward for this issue? Can somehow prove/disprove > > it's qemu at fault? > > I've reproduced this crash (by taking [1] and changing > sys_memfd_create to 279), but it manifests as a normal null-ptr-deref > for me. I'm using the latest QEMU master. Which QEMU does syzbot use > exactly? qemu-system-aarch64 5.2 from this container: https://github.com/google/syzkaller/blob/master/tools/docker/syzbot/Dockerfile you can get a prebuilt version with: docker pull gcr.io/syzkaller/syzbot > [1] https://syzkaller.appspot.com/text?tag=ReproC&x=14d3621cd00000 > > -- > You received this message because you are subscribed to the Google Groups "syzkaller-bugs" group. > To unsubscribe from this group and stop receiving emails from it, send an email to syzkaller-bugs+unsubscribe@googlegroups.com. > To view this discussion on the web visit https://groups.google.com/d/msgid/syzkaller-bugs/CAAeHK%2ByWe_GRDi8j7aPZAauTrfdjgYpYoj9F_KrsG3vtHDwTsw%40mail.gmail.com. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel