From: Ronnie Sahlberg <lsahlber@redhat.com>
Date: Thu, 25 Feb 2021 17:36:27 +1000
Subject: [PATCH] cifs: fix handling of escaped ',' in the password mount
 argument
Git-commit: d08395a3f2f473c6ceeb316a1aeb7fad5b43014f
Patch-mainline: v5.12-rc1
References: bsc#1192606

Passwords can contain ',' which are also used as the separator between
mount options. Mount.cifs will escape all ',' characters as the string ",,".
Update parsing of the mount options to detect ",," and treat it as a single
'c' character.

Fixes: 24e0a1eff9e2 ("cifs: switch to new mount api")
Cc: stable@vger.kernel.org # 5.11
Reported-by: Simon Taylor <simon@simon-taylor.me.uk>
Tested-by: Simon Taylor <simon@simon-taylor.me.uk>
Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Acked-by: Enzo Matsumiya <ematsumiya@suse.de>
---
 fs/cifs/fs_context.c | 43 ++++++++++++++++++++++++++++++-------------
 1 file changed, 30 insertions(+), 13 deletions(-)

diff --git a/fs/cifs/fs_context.c b/fs/cifs/fs_context.c
index 14c955a30006..892f51a21278 100644
--- a/fs/cifs/fs_context.c
+++ b/fs/cifs/fs_context.c
@@ -544,20 +544,37 @@ static int smb3_fs_context_parse_monolithic(struct fs_context *fc,
 
 	/* BB Need to add support for sep= here TBD */
 	while ((key = strsep(&options, ",")) != NULL) {
-		if (*key) {
-			size_t v_len = 0;
-			char *value = strchr(key, '=');
-
-			if (value) {
-				if (value == key)
-					continue;
-				*value++ = 0;
-				v_len = strlen(value);
-			}
-			ret = vfs_parse_fs_string(fc, key, value, v_len);
-			if (ret < 0)
-				break;
+		size_t len;
+		char *value;
+
+		if (*key == 0)
+			break;
+
+		/* Check if following character is the deliminator If yes,
+		 * we have encountered a double deliminator reset the NULL
+		 * character to the deliminator
+		 */
+		while (options && options[0] == ',') {
+			len = strlen(key);
+			strcpy(key + len, options);
+			options = strchr(options, ',');
+			if (options)
+				*options++ = 0;
 		}
+
+
+		len = 0;
+		value = strchr(key, '=');
+		if (value) {
+			if (value == key)
+				continue;
+			*value++ = 0;
+			len = strlen(value);
+		}
+
+		ret = vfs_parse_fs_string(fc, key, value, len);
+		if (ret < 0)
+			break;
 	}
 
 	return ret;
-- 
2.33.1