fuse: readdir: check for slash in names

Userspace can add names containing a slash character to the directory
listing.  Don't allow this as it could cause all sorts of trouble.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Cc: stable@vger.kernel.org

fs/fuse/dir.c

@@ -1174,6 +1174,8 @@ static int parse_dirfile(char *buf, size_t nbytes, struct file *file,
 			return -EIO;
 		if (reclen > nbytes)
 			break;
+		if (memchr(dirent->name, '/', dirent->namelen) != NULL)
+			return -EIO;
 
 		if (!dir_emit(ctx, dirent->name, dirent->namelen,
 			       dirent->ino, dirent->type))
@@ -1320,6 +1322,8 @@ static int parse_dirplusfile(char *buf, size_t nbytes, struct file *file,
 			return -EIO;
 		if (reclen > nbytes)
 			break;
+		if (memchr(dirent->name, '/', dirent->namelen) != NULL)
+			return -EIO;
 
 		if (!over) {
 			/* We fill entries into dstbuf only as much as