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 01F01C433F5 for ; Tue, 7 Dec 2021 01:56:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239507AbhLGCAP (ORCPT ); Mon, 6 Dec 2021 21:00:15 -0500 Received: from ams.source.kernel.org ([145.40.68.75]:43692 "EHLO ams.source.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238691AbhLGCAF (ORCPT ); Mon, 6 Dec 2021 21:00:05 -0500 Received: from mail.kernel.org (unknown [198.145.29.99]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id E232CB8166D for ; Tue, 7 Dec 2021 01:56:34 +0000 (UTC) Received: by mail.kernel.org (Postfix) with ESMTPSA id E447C60EBB; Tue, 7 Dec 2021 01:56:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1638842193; bh=b/VP2yUNSXMDqDOnbHgxx09MYMM/sNMmnDNOVdXb0RA=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=vMSNbM8vZIsAGf8maRR7w/w9aK/geHLwbvw6fpxURpdRkbnYmVEbDgmml5+wNq18w DhBpbpTkWmSaKxvHRdTOe64utAVXdk7dvIc57DRsP5ZY6jqygza+X22PWlZQ3zj/uk TEXiI/7MAvCoYYqT1cNmoOSWIJjhzwefEMYmKSjk= Date: Mon, 6 Dec 2021 17:56:31 -0800 From: Andrew Morton To: syzbot Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, syzkaller-bugs@googlegroups.com, linux-f2fs-devel@lists.sourceforge.net, Matthew Wilcox Subject: Re: [syzbot] BUG: unable to handle kernel NULL pointer dereference in folio_mark_dirty Message-Id: <20211206175631.5d0c3caefa96f0479f0fc2e8@linux-foundation.org> In-Reply-To: <0000000000005f297e05d24f05f6@google.com> References: <0000000000005f297e05d24f05f6@google.com> X-Mailer: Sylpheed 3.5.1 (GTK+ 2.24.31; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, 04 Dec 2021 01:55:17 -0800 syzbot wrote: > Hello, > > syzbot found the following issue on: > > HEAD commit: 58e1100fdc59 MAINTAINERS: co-maintain random.c > git tree: upstream > console output: https://syzkaller.appspot.com/x/log.txt?x=1362881eb00000 > kernel config: https://syzkaller.appspot.com/x/.config?x=e9ea28d2c3c2c389 > dashboard link: https://syzkaller.appspot.com/bug?extid=7cd473c2cac13fd2dd72 > compiler: Debian clang version 11.0.1-2, GNU ld (GNU Binutils for Debian) 2.35.2 > > 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+7cd473c2cac13fd2dd72@syzkaller.appspotmail.com > > BUG: kernel NULL pointer dereference, address: 0000000000000000 cc linux-f2fs-devel@lists.sourceforge.net And willy, who might help with diagnosing this. But it does seem that f2fs got itself a NULL page* then put it in places where it shouldn't have. > #PF: supervisor instruction fetch in kernel mode > #PF: error_code(0x0010) - not-present page > PGD 70764067 P4D 70764067 PUD 0 > Oops: 0010 [#1] PREEMPT SMP KASAN > CPU: 1 PID: 6541 Comm: syz-executor.3 Not tainted 5.16.0-rc3-syzkaller #0 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 > RIP: 0010:0x0 > Code: Unable to access opcode bytes at RIP 0xffffffffffffffd6. > RSP: 0018:ffffc900027ff7f8 EFLAGS: 00010246 > RAX: 1ffffffff14fef03 RBX: ffffffff8a7f7818 RCX: ffff88801b40d700 > RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffea0002790ec0 > RBP: dffffc0000000000 R08: ffffffff81b0fa16 R09: fffff940004f21d9 > R10: fffff940004f21d9 R11: 0000000000000000 R12: ffff88806c11c7b0 > R13: 0000000000000000 R14: 1ffffd40004f21d9 R15: ffffea0002790ec0 > FS: 0000555557165400(0000) GS:ffff8880b9b00000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: ffffffffffffffd6 CR3: 0000000030d85000 CR4: 00000000003526e0 > Call Trace: > > folio_mark_dirty+0x136/0x270 mm/page-writeback.c:2639 > f2fs_update_meta_page+0x4b/0x380 fs/f2fs/segment.c:2485 > do_checkpoint fs/f2fs/checkpoint.c:1513 [inline] > f2fs_write_checkpoint+0x31ad/0x5430 fs/f2fs/checkpoint.c:1674 > f2fs_issue_checkpoint+0x361/0x4e0 > sync_filesystem+0x19c/0x1f0 fs/sync.c:63 > generic_shutdown_super+0x6b/0x300 fs/super.c:448 > kill_block_super+0x79/0xd0 fs/super.c:1397 > kill_f2fs_super+0x2f9/0x3c0 fs/f2fs/super.c:4478 > deactivate_locked_super+0xa7/0xf0 fs/super.c:335 > cleanup_mnt+0x462/0x510 fs/namespace.c:1137 > task_work_run+0x146/0x1c0 kernel/task_work.c:164 > tracehook_notify_resume include/linux/tracehook.h:189 [inline] > exit_to_user_mode_loop kernel/entry/common.c:175 [inline] > exit_to_user_mode_prepare+0x209/0x220 kernel/entry/common.c:207 > __syscall_exit_to_user_mode_work kernel/entry/common.c:289 [inline] > syscall_exit_to_user_mode+0x2e/0x70 kernel/entry/common.c:300 > do_syscall_64+0x53/0xd0 arch/x86/entry/common.c:86 > entry_SYSCALL_64_after_hwframe+0x44/0xae > RIP: 0033:0x7f6cfdd59f57 > Code: ff ff ff f7 d8 64 89 01 48 83 c8 ff c3 66 0f 1f 44 00 00 31 f6 e9 09 00 00 00 66 0f 1f 84 00 00 00 00 00 b8 a6 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48 > RSP: 002b:00007fffcbddcad8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6 > RAX: 0000000000000000 RBX: 0000000000000000 RCX: 00007f6cfdd59f57 > RDX: 00007fffcbddcbac RSI: 000000000000000a RDI: 00007fffcbddcba0 > RBP: 00007fffcbddcba0 R08: 00000000ffffffff R09: 00007fffcbddc970 > R10: 0000555557166903 R11: 0000000000000246 R12: 00007f6cfddb2105 > R13: 00007fffcbdddc60 R14: 0000555557166810 R15: 00007fffcbdddca0 > > Modules linked in: > CR2: 0000000000000000 > ---[ end trace 08eda5a5e35b48a0 ]--- > RIP: 0010:0x0 > Code: Unable to access opcode bytes at RIP 0xffffffffffffffd6. > RSP: 0018:ffffc900027ff7f8 EFLAGS: 00010246 > RAX: 1ffffffff14fef03 RBX: ffffffff8a7f7818 RCX: ffff88801b40d700 > RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffea0002790ec0 > RBP: dffffc0000000000 R08: ffffffff81b0fa16 R09: fffff940004f21d9 > R10: fffff940004f21d9 R11: 0000000000000000 R12: ffff88806c11c7b0 > R13: 0000000000000000 R14: 1ffffd40004f21d9 R15: ffffea0002790ec0 > FS: 0000555557165400(0000) GS:ffff8880b9b00000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: ffffffffffffffd6 CR3: 0000000030d85000 CR4: 00000000003526e0 > > > --- > This report is generated by a bot. It may contain errors. > See https://goo.gl/tpsmEJ for more information about syzbot. > syzbot engineers can be reached at syzkaller@googlegroups.com. > > syzbot will keep track of this issue. See: > https://goo.gl/tpsmEJ#status for how to communicate with syzbot.