From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 067183D669D; Thu, 15 Jan 2026 17:56:44 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768499804; cv=none; b=P3l0BvnJL0LYM0bl2rCrT+IxBmgraA/2Krl3lnF6/RTV0Gd26z3yMGPmxl8Mlzy4GhGQocfRZsLD37VOw9v5A5dHKMwJXkE4q+PZJiULRLFFuHofikudEhn6pCI1RnHtD01eJnWmW5f895zou0+OG2+yMt8kYuKVBE+RcQs/C9M= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768499804; c=relaxed/simple; bh=jfE4ImJhJmbBa3Jd4VHXvbkZK5t+gplN3Ix3vTaYx+M=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=adpOPqMixk73HMBgNnNv+PY3uUKAhJR9G/PCuKWkRXMebqaiEGZ0umfBQ4yvEpOazn5QtGCBYwTuXRfefLibUalORqIMvkvfa9abbL1fUzSgjkD+dpzHiz64FIHO8ugxRR6a4HFZVrEt3/JhXOI7VnmjwJITKH2dJ2M3Z91/cHw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=aaEnFLv3; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="aaEnFLv3" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 87ED8C116D0; Thu, 15 Jan 2026 17:56:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1768499803; bh=jfE4ImJhJmbBa3Jd4VHXvbkZK5t+gplN3Ix3vTaYx+M=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=aaEnFLv3ovz7yOWB67ehfqoTU7SL6hTe7S8suhQgmr13m/tpAUr0cv++my80yCEcD hxBZPtw6wKBertWUBu+fZV6J3e1n1DrPqCw1v7fJA9GfQqL38eGPOFx9LRrxGFDM/Q wiQ5yhA/qLtvhQRwyVmvUd/g9Hgt1kp/RtSZXZPk= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Fedor Pchelkin , Baokun Li , Jan Kara , Theodore Tso , Sasha Levin Subject: [PATCH 5.10 356/451] ext4: fix string copying in parse_apply_sb_mount_options() Date: Thu, 15 Jan 2026 17:49:17 +0100 Message-ID: <20260115164243.780402081@linuxfoundation.org> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20260115164230.864985076@linuxfoundation.org> References: <20260115164230.864985076@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.10-stable review patch. If anyone has any objections, please let me know. ------------------ From: Fedor Pchelkin [ Upstream commit ee5a977b4e771cc181f39d504426dbd31ed701cc ] strscpy_pad() can't be used to copy a non-NUL-term string into a NUL-term string of possibly bigger size. Commit 0efc5990bca5 ("string.h: Introduce memtostr() and memtostr_pad()") provides additional information in that regard. So if this happens, the following warning is observed: strnlen: detected buffer overflow: 65 byte read of buffer size 64 WARNING: CPU: 0 PID: 28655 at lib/string_helpers.c:1032 __fortify_report+0x96/0xc0 lib/string_helpers.c:1032 Modules linked in: CPU: 0 UID: 0 PID: 28655 Comm: syz-executor.3 Not tainted 6.12.54-syzkaller-00144-g5f0270f1ba00 #0 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 RIP: 0010:__fortify_report+0x96/0xc0 lib/string_helpers.c:1032 Call Trace: __fortify_panic+0x1f/0x30 lib/string_helpers.c:1039 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:2504 [inline] __ext4_fill_super fs/ext4/super.c:5261 [inline] ext4_fill_super+0x3c35/0xad00 fs/ext4/super.c:5706 get_tree_bdev_flags+0x387/0x620 fs/super.c:1636 vfs_get_tree+0x93/0x380 fs/super.c:1814 do_new_mount fs/namespace.c:3553 [inline] path_mount+0x6ae/0x1f70 fs/namespace.c:3880 do_mount fs/namespace.c:3893 [inline] __do_sys_mount fs/namespace.c:4103 [inline] __se_sys_mount fs/namespace.c:4080 [inline] __x64_sys_mount+0x280/0x300 fs/namespace.c:4080 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0x64/0x140 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x76/0x7e Since userspace is expected to provide s_mount_opts field to be at most 63 characters long with the ending byte being NUL-term, use a 64-byte buffer which matches the size of s_mount_opts, so that strscpy_pad() does its job properly. Return with error if the user still managed to provide a non-NUL-term string here. Found by Linux Verification Center (linuxtesting.org) with Syzkaller. Fixes: 8ecb790ea8c3 ("ext4: avoid potential buffer over-read in parse_apply_sb_mount_options()") Cc: stable@vger.kernel.org Signed-off-by: Fedor Pchelkin Reviewed-by: Baokun Li Reviewed-by: Jan Kara Message-ID: <20251101160430.222297-1-pchelkin@ispras.ru> Signed-off-by: Theodore Ts'o [ goto failed_mount instead of return ] Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- fs/ext4/super.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -4282,10 +4282,11 @@ static int ext4_fill_super(struct super_ } if (sbi->s_es->s_mount_opts[0]) { - char s_mount_opts[65]; + char s_mount_opts[64]; - strscpy_pad(s_mount_opts, sbi->s_es->s_mount_opts, - sizeof(s_mount_opts)); + if (strscpy_pad(s_mount_opts, sbi->s_es->s_mount_opts, + sizeof(s_mount_opts)) < 0) + goto failed_mount; if (!parse_options(s_mount_opts, sb, &journal_devnum, &journal_ioprio, 0)) { ext4_msg(sb, KERN_WARNING,