netdev - [PATCH 2/5] netfilter: ebtables: fix erroneous reject of last rule

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Mon, 12 Mar 2018 17:16:01 +0100
From:   Pablo Neira Ayuso <pablo@...filter.org>
To:     netfilter-devel@...r.kernel.org
Cc:     davem@...emloft.net, netdev@...r.kernel.org
Subject: [PATCH 2/5] netfilter: ebtables: fix erroneous reject of last rule

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

The last rule in the blob has next_entry offset that is same as total size.
This made "ebtables32 -A OUTPUT -d de:ad:be:ef:01:02" fail on 64 bit kernel.

Fixes: b71812168571fa ("netfilter: ebtables: CONFIG_COMPAT: don't trust userland offsets")
Signed-off-by: Florian Westphal <fw@...len.de>
Signed-off-by: Pablo Neira Ayuso <pablo@...filter.org>
---
 net/bridge/netfilter/ebtables.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/net/bridge/netfilter/ebtables.c b/net/bridge/netfilter/ebtables.c
index 254ef9f49567..a94d23b0a9af 100644
--- a/net/bridge/netfilter/ebtables.c
+++ b/net/bridge/netfilter/ebtables.c
@@ -2119,8 +2119,12 @@ static int size_entry_mwt(struct ebt_entry *entry, const unsigned char *base,
 	 * offsets are relative to beginning of struct ebt_entry (i.e., 0).
 	 */
 	for (i = 0; i < 4 ; ++i) {
-		if (offsets[i] >= *total)
+		if (offsets[i] > *total)
 			return -EINVAL;
+
+		if (i < 3 && offsets[i] == *total)
+			return -EINVAL;
+
 		if (i == 0)
 			continue;
 		if (offsets[i-1] > offsets[i])
-- 
2.11.0