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 808DF30FF32 for ; Mon, 29 Dec 2025 12:30:11 +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=1767011411; cv=none; b=EZYKRwLtYGCy9JBasqSeFBzbmAKw5vgYjSorMgDGQwOyxr8nhTMoRLIkwfELIwTFiHNjZXB8RbkM6nzmPbwsWIyHhly1DcsyTd1tRJF2sakgbBuXFYMtH/EFeTgVKzeO7KkDZ89ohen2ZjjDvU3NZ+aCrmxp2cXfo4yikuazwAA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767011411; c=relaxed/simple; bh=AIXrxx5m9R3dizSjQSFWtPiV3UrV/asljUfZHxf5XZ4=; h=Subject:To:Cc:From:Date:Message-ID:MIME-Version:Content-Type; b=alshmu9jS5jy4QG+5VDRb2pGdzPjvlKr5l6r1kToFHWtVKUXSBJHdMs8izQAMbNRrV7g69Zr1Bbt34XU75nuC10gZNxu9qVZvcXiYh/9hhOGjM3Xy7mmTHOUFavRcRAGIUo+jdIGRvy1zlApbaZUiB07Pri7BsGlTwhElEL4iqU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=p+A49m3J; 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="p+A49m3J" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 935A4C4CEF7; Mon, 29 Dec 2025 12:30:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1767011410; bh=AIXrxx5m9R3dizSjQSFWtPiV3UrV/asljUfZHxf5XZ4=; h=Subject:To:Cc:From:Date:From; b=p+A49m3J7A1BF2pRVgr0ePch1YwoIL/i3JMTcNRJ2oYJLyXhO4nmDxdiz77wUk5Vr iKS7FaZMCW4xbz+GfsCFYy7tny90+K88AZMEKwD/WnMtClk14UJCA8lNWG3zXHqBAv 3l8Si6cRtZ5Pu3PhSWdurfv5NNqH0c6nB8w1WL5U= Subject: FAILED: patch "[PATCH] ext4: fix string copying in parse_apply_sb_mount_options()" failed to apply to 5.15-stable tree To: pchelkin@ispras.ru,jack@suse.cz,libaokun1@huawei.com,tytso@mit.edu Cc: From: Date: Mon, 29 Dec 2025 13:29:58 +0100 Message-ID: <2025122958-ambitious-prenatal-99c2@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit The patch below does not apply to the 5.15-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y git checkout FETCH_HEAD git cherry-pick -x ee5a977b4e771cc181f39d504426dbd31ed701cc # git commit -s git send-email --to '' --in-reply-to '2025122958-ambitious-prenatal-99c2@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^.. Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From ee5a977b4e771cc181f39d504426dbd31ed701cc Mon Sep 17 00:00:00 2001 From: Fedor Pchelkin Date: Sat, 1 Nov 2025 19:04:28 +0300 Subject: [PATCH] ext4: fix string copying in parse_apply_sb_mount_options() 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 diff --git a/fs/ext4/super.c b/fs/ext4/super.c index 7de15249e826..d1ba894c0e0a 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -2476,7 +2476,7 @@ static int parse_apply_sb_mount_options(struct super_block *sb, struct ext4_fs_context *m_ctx) { struct ext4_sb_info *sbi = EXT4_SB(sb); - char s_mount_opts[65]; + char s_mount_opts[64]; struct ext4_fs_context *s_ctx = NULL; struct fs_context *fc = NULL; int ret = -ENOMEM; @@ -2484,7 +2484,8 @@ static int parse_apply_sb_mount_options(struct super_block *sb, if (!sbi->s_es->s_mount_opts[0]) return 0; - strscpy_pad(s_mount_opts, sbi->s_es->s_mount_opts); + if (strscpy_pad(s_mount_opts, sbi->s_es->s_mount_opts) < 0) + return -E2BIG; fc = kzalloc(sizeof(struct fs_context), GFP_KERNEL); if (!fc)