fuse: readdir: check for slash in names

commit efeb9e60d48f7778fdcad4a0f3ad9ea9b19e5dfd upstream.

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>
[bwh: Backported to 3.2: drop changes to parse_dirplusfile() which we
 don't have]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Cc: Rui Xiang <rui.xiang@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c
index 373b251..9966cae 100644
--- a/fs/fuse/dir.c
+++ b/fs/fuse/dir.c
@@ -1103,6 +1103,8 @@
 			return -EIO;
 		if (reclen > nbytes)
 			break;
+		if (memchr(dirent->name, '/', dirent->namelen) != NULL)
+			return -EIO;
 
 		over = filldir(dstbuf, dirent->name, dirent->namelen,
 			       file->f_pos, dirent->ino, dirent->type);