From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.15]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B0A383D301F; Fri, 6 Feb 2026 14:20:20 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.175.65.15 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770387622; cv=none; b=jlN54921ZrT0h9onGveDqRSe4BMOyc6fSPafn7XvnXPk39yOZz7g+VzdRrdvxXUZIFSxne5Q8xOydy7VBucxKbI5mCLNC+Bat66diL+uJF1oRi3yCM4VLZnBz+r23t2WFE0EGSxQyui0jjcHnpCJrBaUd9A4lCJGK3P5Wb9TQ1I= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770387622; c=relaxed/simple; bh=uCTjK/Y0kFMcypq3m/UrIiqMil9+P7DfzqeY+hnGZNo=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=DCJTkFO5nTnyf8qKyPpMs332NM+sdb3jI1fuNeb+P5JvviZrUGobnLcw3QA2akCOVCYt/lR5Po25n69WXp2vhl6t0FyJqGbhR7scfKpvxa4Ftd5ZsLoK1QNHdatxP6EKoiVoYMaDIWyslio5uitV8uvJuZEbEdehOZE8lU9Y+rA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com; spf=pass smtp.mailfrom=intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=IuSoCLRs; arc=none smtp.client-ip=198.175.65.15 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="IuSoCLRs" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1770387621; x=1801923621; h=date:from:to:cc:subject:message-id:references: mime-version:content-transfer-encoding:in-reply-to; bh=uCTjK/Y0kFMcypq3m/UrIiqMil9+P7DfzqeY+hnGZNo=; b=IuSoCLRsje0DhOTeMI+a3VP6OCDtaURmohsCdkxOxjpCkaYZ5LIZzEvd wZSWDSlanWUmZxC+8Mf9V7eXLIy8QDCc93+1JHrSAE2QZcbzyq7jJXE3r 5a7HmTstWLgFNfPh165SOfJjmbAs14HBVyBud93eNiXV6kHdBQcvdbUdP 0ZAmXv5RLlcEeYqJuQs/B8JQ/Fl5CUFFlxOjLUiSOgrasxg2MVro+UmO/ 218FeSw5CxvTDqHMebeohqR4B+MLJzfeGIOly5Tcb07xTcN8Qw0LMmqbI 8O3gN1U0FZEk7urk7k8t4Iiw58K/TcZNQpzw8Ie46QI4tN+Dfxy/5LSBW w==; X-CSE-ConnectionGUID: FHTVssddRiSl2Z77OV+ZfA== X-CSE-MsgGUID: l6yro6JUR46UmNwDME6pNQ== X-IronPort-AV: E=McAfee;i="6800,10657,11693"; a="75212717" X-IronPort-AV: E=Sophos;i="6.21,276,1763452800"; d="scan'208";a="75212717" Received: from fmviesa002.fm.intel.com ([10.60.135.142]) by orvoesa107.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 06 Feb 2026 06:20:20 -0800 X-CSE-ConnectionGUID: PA7dGKLlSXitAghISqB7eg== X-CSE-MsgGUID: ygzttfDSSFePBMoGVK9j4g== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.21,276,1763452800"; d="scan'208";a="233825471" Received: from ijarvine-mobl1.ger.corp.intel.com (HELO localhost) ([10.245.244.202]) by fmviesa002-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 06 Feb 2026 06:20:17 -0800 Date: Fri, 6 Feb 2026 16:20:15 +0200 From: Andy Shevchenko To: =?utf-8?B?5p2O6b6Z5YW0?= , Theodore Ts'o , Andreas Dilger , linux-ext4@vger.kernel.org Cc: syzkaller@googlegroups.com, kees@kernel.org, andy@kernel.org, akpm@linux-foundation.org, linux-hardening@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [Kernel Bug] WARNING in ext4_fill_super Message-ID: References: Precedence: bulk X-Mailing-List: linux-hardening@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Organization: Intel Finland Oy - BIC 0357606-4 - c/o Alberga Business Park, 6 krs, Bertel Jungin Aukio 5, 02600 Espoo On Mon, Feb 02, 2026 at 12:19:45PM +0800, 李龙兴 wrote: > Dear Linux kernel developers and maintainers, > > We would like to report a new kernel bug found by our tool. The issue > is a WARNING in ext4_fill_super. Details are as follows. First of all, the warning appears in parse_apply_sb_mount_options(). > Kernel commit: v6.18.2 > Kernel config: see attachment > report: see attachment Second, you should include people based on the actual subsystem, unless it's proven that the problem is in lib/*. Cc'ed to ext4. > We are currently analyzing the root cause and working on a > reproducible PoC. We will provide further updates in this thread as > soon as we have more information. > loop4: detected capacity change from 0 to 514 > ------------[ cut here ]------------ > strnlen: detected buffer overflow: 65 byte read of buffer size 64 > WARNING: CPU: 0 PID: 12320 at lib/string_helpers.c:1035 > __fortify_report+0x9c/0xd0 lib/string_helpers.c:1035 > Modules linked in: > CPU: 0 UID: 0 PID: 12320 Comm: syz.4.59 Not tainted 6.18.2 #1 PREEMPT(full) > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014 > RIP: 0010:__fortify_report+0x9c/0xd0 lib/string_helpers.c:1035 > Code: ed 48 c7 c0 80 c8 cf 8b 48 0f 44 d8 e8 cd dd 17 fd 4d 89 e0 48 > 89 ea 4c 89 f6 48 89 d9 48 c7 c7 00 c9 cf 8b e8 b5 57 d6 fc 90 <0f> 0b > 90 90 5b 5d 41 5c 41 5d 41 5e c3 cc cc cc cc 48 89 de 48 c7 > RSP: 0018:ffffc90011f9fa18 EFLAGS: 00010282 > RAX: 0000000000000000 RBX: ffffffff8bcfc880 RCX: ffffffff817afc38 > RDX: ffff8881095eca80 RSI: ffffffff817afc45 RDI: 0000000000000001 > RBP: 0000000000000041 R08: 0000000000000001 R09: 0000000000000000 > R10: 0000000000000001 R11: 0000000000000001 R12: 0000000000000040 > R13: 0000000000000000 R14: ffffffff8bcfd240 R15: ffff88803c484400 > FS: 00007f9e5f45c640(0000) GS:ffff8880cf053000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 0000000000000000 CR3: 0000000123400000 CR4: 0000000000752ef0 > PKRU: 80000000 > Call Trace: > > __fortify_panic+0x23/0x30 lib/string_helpers.c:1042 > strnlen include/linux/fortify-string.h:235 [inline] > sized_strscpy include/linux/fortify-string.h:309 [inline] > parse_apply_sb_mount_options fs/ext4/super.c:2486 [inline] > __ext4_fill_super fs/ext4/super.c:5306 [inline] > ext4_fill_super+0x3972/0xaf70 fs/ext4/super.c:5736 > get_tree_bdev_flags+0x38c/0x620 fs/super.c:1698 > vfs_get_tree+0x8e/0x340 fs/super.c:1758 > fc_mount fs/namespace.c:1199 [inline] > do_new_mount_fc fs/namespace.c:3642 [inline] > do_new_mount fs/namespace.c:3718 [inline] > path_mount+0x7b9/0x23a0 fs/namespace.c:4028 > do_mount fs/namespace.c:4041 [inline] > __do_sys_mount fs/namespace.c:4229 [inline] > __se_sys_mount fs/namespace.c:4206 [inline] > __x64_sys_mount+0x293/0x310 fs/namespace.c:4206 > do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] > do_syscall_64+0xcd/0xfa0 arch/x86/entry/syscall_64.c:94 > entry_SYSCALL_64_after_hwframe+0x77/0x7f > RIP: 0033:0x56755e > Code: 48 c7 c0 ff ff ff ff eb aa e8 3e 1c 00 00 66 2e 0f 1f 84 00 00 > 00 00 00 0f 1f 40 00 f3 0f 1e fa 49 89 ca b8 a5 00 00 00 0f 05 <48> 3d > 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48 > RSP: 002b:00007f9e5f45bdf8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5 > RAX: ffffffffffffffda RBX: 00007f9e5f45be80 RCX: 000000000056755e > RDX: 0000000020000140 RSI: 0000000020000440 RDI: 00007f9e5f45be40 > RBP: 0000000020000140 R08: 00007f9e5f45be80 R09: 0000000000000000 > R10: 0000000000000000 R11: 0000000000000246 R12: 0000000020000440 > R13: 00007f9e5f45be40 R14: 00000000000003d5 R15: 0000000020000200 > > > https://drive.google.com/file/d/12W8B3IU88RBdBpV4nMcAj9TVOzlx6xL-/ > https://drive.google.com/file/d/1efTUJTmSTMuJqSpCq686RjXdUzhyEJDL/ -- With Best Regards, Andy Shevchenko