netdev - [PATCH 08/10] netfilter: ebtables: CONFIG_COMPAT: drop a bogus WARN

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Message-Id: <20190422204801.26321-9-pablo@netfilter.org>
Date:   Mon, 22 Apr 2019 22:47:59 +0200
From:   Pablo Neira Ayuso <pablo@...filter.org>
To:     netfilter-devel@...r.kernel.org
Cc:     davem@...emloft.net, netdev@...r.kernel.org
Subject: [PATCH 08/10] netfilter: ebtables: CONFIG_COMPAT: drop a bogus WARN_ON

From: Florian Westphal <fw@...len.de>

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@...kaller.appspotmail.com
Signed-off-by: Florian Westphal <fw@...len.de>
Signed-off-by: Pablo Neira Ayuso <pablo@...filter.org>
---
 net/bridge/netfilter/ebtables.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/bridge/netfilter/ebtables.c b/net/bridge/netfilter/ebtables.c
index eb15891f8b9f..3cad01ac64e4 100644
--- 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;
-- 
2.11.0