fs, omfs: add NULL terminator in the end up the token list

commit dcbff39d upstream.

match_token() expects a NULL terminator at the end of the token list so
that it would know where to stop.  Not having one causes it to overrun
to invalid memory.

In practice, passing a mount option that omfs didn't recognize would
sometimes panic the system.
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
Signed-off-by: Bob Copeland <me@bobcopeland.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>

fs/omfs/inode.c

@@ -361,7 +361,7 @@ static int omfs_get_imap(struct super_block *sb)
 }
 
 enum {
-	Opt_uid, Opt_gid, Opt_umask, Opt_dmask, Opt_fmask
+	Opt_uid, Opt_gid, Opt_umask, Opt_dmask, Opt_fmask, Opt_err
 };
 
 static const match_table_t tokens = {
@@ -370,6 +370,7 @@ static const match_table_t tokens = {
 	{Opt_umask, "umask=%o"},
 	{Opt_dmask, "dmask=%o"},
 	{Opt_fmask, "fmask=%o"},
+	{Opt_err, NULL},
 };
 
 static int parse_options(char *options, struct omfs_sb_info *sbi)