net: team: fix memory leak in __team_options_register

The variable "i" isn't initialized back correctly after the first loop
under the label inst_rollback gets executed.

The value of "i" is assigned to be option_count - 1, and the ensuing
loop (under alloc_rollback) begins by initializing i--.
Thus, the value of i when the loop begins execution will now become
i = option_count - 2.

Thus, when kfree(dst_opts[i]) is called in the second loop in this
order, (i.e., inst_rollback followed by alloc_rollback),
dst_optsp[option_count - 2] is the first element freed, and
dst_opts[option_count - 1] does not get freed, and thus, a memory
leak is caused.

This memory leak can be fixed, by assigning i = option_count (instead of
option_count - 1).

Fixes: 80f7c668 ("team: add support for per-port options")
Reported-by: syzbot+69b804437cfec30deac3@syzkaller.appspotmail.com
Tested-by: syzbot+69b804437cfec30deac3@syzkaller.appspotmail.com
Signed-off-by: Anant Thazhemadam <anant.thazhemadam@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/team/team.c

@@ -287,7 +287,7 @@ static int __team_options_register(struct team *team,
 	for (i--; i >= 0; i--)
 		__team_option_inst_del_option(team, dst_opts[i]);
 
-	i = option_count - 1;
+	i = option_count;
 alloc_rollback:
 	for (i--; i >= 0; i--)
 		kfree(dst_opts[i]);