linux-kernel - [PATCH 3.16 102/157] netfilter: ebtables: CONFIG_COMPAT: drop a bogus WARN

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Message-ID: <lsq.1565469607.328511265@decadent.org.uk>
Date:   Sat, 10 Aug 2019 21:40:07 +0100
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, Denis Kirjanov <kda@...ux-powerpc.org>,
        "Florian Westphal" <fw@...len.de>,
        syzbot+659574e7bcc7f7eb4df7@...kaller.appspotmail.com,
        "Pablo Neira Ayuso" <pablo@...filter.org>
Subject: [PATCH 3.16 102/157] netfilter: ebtables: CONFIG_COMPAT: drop a
 bogus WARN_ON

3.16.72-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Florian Westphal <fw@...len.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@...kaller.appspotmail.com
Signed-off-by: Florian Westphal <fw@...len.de>
Signed-off-by: Pablo Neira Ayuso <pablo@...filter.org>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 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
@@ -2011,7 +2011,8 @@ 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;