From: Pablo Neira Ayuso <pablo@netfilter.org>
To: netfilter-devel@vger.kernel.org
Cc: davem@davemloft.net, netdev@vger.kernel.org
Subject: [PATCH 04/14] netfilter: bridge: ebt_among: add missing match size checks
Date: Fri, 2 Mar 2018 21:32:52 +0100 [thread overview]
Message-ID: <20180302203302.3724-5-pablo@netfilter.org> (raw)
In-Reply-To: <20180302203302.3724-1-pablo@netfilter.org>
From: Florian Westphal <fw@strlen.de>
ebt_among is special, it has a dynamic match size and is exempt
from the central size checks.
Therefore it must check that the size of the match structure
provided from userspace is sane by making sure em->match_size
is at least the minimum size of the expected structure.
The module has such a check, but its only done after accessing
a structure that might be out of bounds.
tested with: ebtables -A INPUT ... \
--among-dst fe:fe:fe:fe:fe:fe
--among-dst fe:fe:fe:fe:fe:fe --among-src fe:fe:fe:fe:ff:f,fe:fe:fe:fe:fe:fb,fe:fe:fe:fe:fc:fd,fe:fe:fe:fe:fe:fd,fe:fe:fe:fe:fe:fe
--among-src fe:fe:fe:fe:ff:f,fe:fe:fe:fe:fe:fa,fe:fe:fe:fe:fe:fd,fe:fe:fe:fe:fe:fe,fe:fe:fe:fe:fe:fe
Reported-by: <syzbot+fe0b19af568972814355@syzkaller.appspotmail.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
net/bridge/netfilter/ebt_among.c | 21 +++++++++++++++++++--
1 file changed, 19 insertions(+), 2 deletions(-)
diff --git a/net/bridge/netfilter/ebt_among.c b/net/bridge/netfilter/ebt_among.c
index ce7152a12bd8..c5afb4232ecb 100644
--- a/net/bridge/netfilter/ebt_among.c
+++ b/net/bridge/netfilter/ebt_among.c
@@ -172,18 +172,35 @@ ebt_among_mt(const struct sk_buff *skb, struct xt_action_param *par)
return true;
}
+static bool poolsize_invalid(const struct ebt_mac_wormhash *w)
+{
+ return w && w->poolsize >= (INT_MAX / sizeof(struct ebt_mac_wormhash_tuple));
+}
+
static int ebt_among_mt_check(const struct xt_mtchk_param *par)
{
const struct ebt_among_info *info = par->matchinfo;
const struct ebt_entry_match *em =
container_of(par->matchinfo, const struct ebt_entry_match, data);
- int expected_length = sizeof(struct ebt_among_info);
+ unsigned int expected_length = sizeof(struct ebt_among_info);
const struct ebt_mac_wormhash *wh_dst, *wh_src;
int err;
+ if (expected_length > em->match_size)
+ return -EINVAL;
+
wh_dst = ebt_among_wh_dst(info);
- wh_src = ebt_among_wh_src(info);
+ if (poolsize_invalid(wh_dst))
+ return -EINVAL;
+
expected_length += ebt_mac_wormhash_size(wh_dst);
+ if (expected_length > em->match_size)
+ return -EINVAL;
+
+ wh_src = ebt_among_wh_src(info);
+ if (poolsize_invalid(wh_src))
+ return -EINVAL;
+
expected_length += ebt_mac_wormhash_size(wh_src);
if (em->match_size != EBT_ALIGN(expected_length)) {
--
2.11.0
next prev parent reply other threads:[~2018-03-02 20:33 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-02 20:32 [PATCH 00/14] Netfilter/IPVS fixes for net Pablo Neira Ayuso
2018-03-02 20:32 ` [PATCH 01/14] netfilter: ipt_CLUSTERIP: put config struct if we can't increment ct refcount Pablo Neira Ayuso
2018-03-02 20:32 ` [PATCH 02/14] netfilter: ipt_CLUSTERIP: put config instead of freeing it Pablo Neira Ayuso
2018-03-02 20:32 ` [PATCH 03/14] netfilter: ipv6: fix use-after-free Write in nf_nat_ipv6_manip_pkt Pablo Neira Ayuso
2018-03-02 20:32 ` Pablo Neira Ayuso [this message]
2018-03-02 20:32 ` [PATCH 05/14] netfilter: ebtables: convert BUG_ONs to WARN_ONs Pablo Neira Ayuso
2018-03-02 20:32 ` [PATCH 06/14] netfilter: ebtables: CONFIG_COMPAT: don't trust userland offsets Pablo Neira Ayuso
2018-03-02 20:32 ` [PATCH 07/14] netfilter: nf_flow_table: fix checksum when handling DNAT Pablo Neira Ayuso
2018-03-02 20:32 ` [PATCH 08/14] netfilter: increase IPSTATS_MIB_CSUMERRORS stat Pablo Neira Ayuso
2018-03-02 20:32 ` [PATCH 09/14] netfilter: don't set F_IFACE on ipv6 fib lookups Pablo Neira Ayuso
2018-03-02 20:32 ` [PATCH 10/14] netfilter: use skb_to_full_sk in ip6_route_me_harder Pablo Neira Ayuso
2018-03-02 20:32 ` [PATCH 11/14] netfilter: nf_tables: return EBUSY if device already belongs to flowtable Pablo Neira Ayuso
2018-03-02 20:33 ` [PATCH 12/14] netfilter: nf_tables: missing attribute validation in nf_tables_delflowtable() Pablo Neira Ayuso
2018-03-02 20:33 ` [PATCH 13/14] netfilter: nf_tables: use the right index from flowtable error path Pablo Neira Ayuso
2018-03-02 20:33 ` [PATCH 14/14] ipvs: remove IPS_NAT_MASK check to fix passive FTP Pablo Neira Ayuso
2018-03-03 1:32 ` [PATCH 00/14] Netfilter/IPVS fixes for net David Miller
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