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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org,
        syzbot+659574e7bcc7f7eb4df7@syzkaller.appspotmail.com,
        Florian Westphal <fw@strlen.de>,
        Pablo Neira Ayuso <pablo@netfilter.org>
Subject: [PATCH 3.18 09/86] netfilter: ebtables: CONFIG_COMPAT: drop a bogus WARN_ON
Date:   Wed, 15 May 2019 12:54:46 +0200
Message-Id: <20190515090644.373933627@linuxfoundation.org>
In-Reply-To: <20190515090642.339346723@linuxfoundation.org>
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From: Florian Westphal <fw@strlen.de>

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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 net/bridge/netfilter/ebtables.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/net/bridge/netfilter/ebtables.c
+++ b/net/bridge/netfilter/ebtables.c
@@ -2042,7 +2042,8 @@ static int ebt_size_mwt(struct compat_eb
 		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;