ROMFS: romfs_lookup() shouldn't be doing a partial name comparison

romfs_lookup() should be using a routine akin to strcmp() on the backing store,
rather than one akin to strncmp().  If it uses the latter, it's liable to match
/bin/shutdown when looking up /bin/sh.

Signed-off-by: David Howells <dhowells@redhat.com>
Tested-by: Michal Simek <monstr@monstr.eu>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/fs/romfs/super.c b/fs/romfs/super.c
index 10ca7d9..c53b5ef 100644
--- a/fs/romfs/super.c
+++ b/fs/romfs/super.c
@@ -240,8 +240,8 @@
 			goto error;
 
 		/* try to match the first 16 bytes of name */
-		ret = romfs_dev_strncmp(dir->i_sb, offset + ROMFH_SIZE, name,
-					len);
+		ret = romfs_dev_strcmp(dir->i_sb, offset + ROMFH_SIZE, name,
+				       len);
 		if (ret < 0)
 			goto error;
 		if (ret == 1)