cifs: sanitize paths in cifs_update_super_prepath.

After a server reboot, clients are failing to move files with ENOENT.
This is caused by DFS referrals containing multiple separators, which
the server move call doesn't recognize.

BugLink: https://bugzilla.redhat.com/show_bug.cgi?id=2182472
Fixes: a310808 ("cifs: sanitize multiple delimiters in prepath")
Actually-Fixes: 24e0a1e ("cifs: switch to new mount api")
Signed-off-by: Thiago Rafael Becker <tbecker@redhat.com>

fs/cifs/fs_context.c

@@ -445,7 +445,7 @@ int smb3_parse_opt(const char *options, const char *key, char **val)
  * cleaning up the original.
  */
 #define IS_DELIM(c) ((c) == '/' || (c) == '\\')
-static char *sanitize_path(char *path)
+char *sanitize_path(char *path, gfp_t gfp)
 {
 	char *cursor1 = path, *cursor2 = path;
 
@@ -469,7 +469,7 @@ static char *sanitize_path(char *path)
 		cursor2--;
 
 	*(cursor2) = '\0';
-	return kstrdup(path, GFP_KERNEL);
+	return kstrdup(path, gfp);
 }
 
 /*
@@ -531,7 +531,7 @@ smb3_parse_devname(const char *devname, struct smb3_fs_context *ctx)
 	if (!*pos)
 		return 0;
 
-	ctx->prepath = sanitize_path(pos);
+	ctx->prepath = sanitize_path(pos, GFP_KERNEL);
 	if (!ctx->prepath)
 		return -ENOMEM;
 

fs/cifs/misc.c

@@ -1190,12 +1190,14 @@ int match_target_ip(struct TCP_Server_Info *server,
 	return 0;
 }
 
+extern char *sanitize_path(char *path, gfp_t gfp);
+
 int cifs_update_super_prepath(struct cifs_sb_info *cifs_sb, char *prefix)
 {
 	kfree(cifs_sb->prepath);
 
 	if (prefix && *prefix) {
-		cifs_sb->prepath = kstrdup(prefix, GFP_ATOMIC);
+		cifs_sb->prepath = sanitize_path(prefix, GFP_ATOMIC);
 		if (!cifs_sb->prepath)
 			return -ENOMEM;