netfilter: ebtables: CONFIG_COMPAT: drop a bogus WARN_ON

It means userspace gave us a ruleset where there is some other
data after the ebtables target but before the beginning of the next rule.

Fixes: 81e675c227ec ("netfilter: ebtables: add CONFIG_COMPAT support")
Reported-by: syzbot+659574e7bcc7f7eb4df7@syzkaller.appspotmail.com
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

diff --git a/net/bridge/netfilter/ebtables.c b/net/bridge/netfilter/ebtables.c
index eb15891f8b9ff18842b7d43e96c75733ef7aaa99..3cad01ac64e4a2a5ebcafa394d04cc4415c7ddab 100644 (file)
--- a/net/bridge/netfilter/ebtables.c
+++ b/net/bridge/netfilter/ebtables.c
@@ -2032,7 +2032,8 @@ static int ebt_size_mwt(struct compat_ebt_entry_mwt *match32,
                if (match_kern)
                        match_kern->match_size = ret;
 
-               if (WARN_ON(type == EBT_COMPAT_TARGET && size_left))
+               /* rule should have no remaining data after target */
+               if (type == EBT_COMPAT_TARGET && size_left)
                        return -EINVAL;
 
                match32 = (struct compat_ebt_entry_mwt *) buf;