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 244AB1ED38 for ; Tue, 25 Jul 2023 11:24:26 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9C0A9C433C8; Tue, 25 Jul 2023 11:24:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1690284266; bh=bjrSqabvemZeQb5iQWlfFvOhWAbQi2nX3Esbd/KhKbg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=P6cJQ68Tlf+WJIW/9rcD5WjjXAZUOTZvVLY9xFFDn+GQMIFYuYeX6Lt/22sSCPLZF sEMyq086hCe1kjvh+bxEdEpXD1Ya5T9OZnSnC6Xwu2uZhuQCSP2YwEIZt7F3/O8K0P KBXueanIYxTYFJlFRoOAqp/oXO4d6aUJOEI02tL0= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, =?UTF-8?q?Thomas=20Wei=C3=9Fschuh?= , Christian Brauner Subject: [PATCH 5.10 295/509] fs: avoid empty option when generating legacy mount string Date: Tue, 25 Jul 2023 12:43:54 +0200 Message-ID: <20230725104607.251437580@linuxfoundation.org> X-Mailer: git-send-email 2.41.0 In-Reply-To: <20230725104553.588743331@linuxfoundation.org> References: <20230725104553.588743331@linuxfoundation.org> User-Agent: quilt/0.67 Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Thomas Weißschuh commit 62176420274db5b5127cd7a0083a9aeb461756ee upstream. As each option string fragment is always prepended with a comma it would happen that the whole string always starts with a comma. This could be interpreted by filesystem drivers as an empty option and may produce errors. For example the NTFS driver from ntfs.ko behaves like this and fails when mounted via the new API. Link: https://github.com/util-linux/util-linux/issues/2298 Signed-off-by: Thomas Weißschuh Fixes: 3e1aeb00e6d1 ("vfs: Implement a filesystem superblock creation/configuration context") Cc: stable@vger.kernel.org Message-Id: <20230607-fs-empty-option-v1-1-20c8dbf4671b@weissschuh.net> Signed-off-by: Christian Brauner Signed-off-by: Greg Kroah-Hartman --- fs/fs_context.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) --- a/fs/fs_context.c +++ b/fs/fs_context.c @@ -543,7 +543,8 @@ static int legacy_parse_param(struct fs_ return -ENOMEM; } - ctx->legacy_data[size++] = ','; + if (size) + ctx->legacy_data[size++] = ','; len = strlen(param->key); memcpy(ctx->legacy_data + size, param->key, len); size += len;