netfilter: ebtables: CONFIG_COMPAT: drop a bogus WARN_ON

commit 7caa56f006e9d712b44f27b32520c66420d5cbc6 upstream.

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>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/net/bridge/netfilter/ebtables.c b/net/bridge/netfilter/ebtables.c
index 2df71bc7959daef587e0d87911d57504239e5ed1..75929f9bd4e6b26497a51073742ef473c8deb28a 100644 (file)
--- a/net/bridge/netfilter/ebtables.c
+++ b/net/bridge/netfilter/ebtables.c
@@ -2011,7 +2011,8 @@ 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;