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From: Will McVicker <willmcvicker@google.com>
To: stable@vger.kernel.org, Pablo Neira Ayuso <pablo@netfilter.org>,
	Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>,
	Florian Westphal <fw@strlen.de>
Cc: "David S. Miller" <davem@davemloft.net>,
	Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>,
	Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>,
	netfilter-devel@vger.kernel.org, coreteam@netfilter.org,
	netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
	kernel-team@android.com, Will McVicker <willmcvicker@google.com>
Subject: [PATCH v3 1/1] netfilter: nat: add a range check for l3/l4 protonum
Date: Mon, 24 Aug 2020 19:38:32 +0000	[thread overview]
Message-ID: <20200824193832.853621-2-willmcvicker@google.com> (raw)
In-Reply-To: <20200824193832.853621-1-willmcvicker@google.com>

The indexes to the nf_nat_l[34]protos arrays come from userspace. So
check the tuple's family, e.g. l3num, when creating the conntrack in
order to prevent an OOB memory access during setup.  Here is an example
kernel panic on 4.14.180 when userspace passes in an index greater than
NFPROTO_NUMPROTO.

Internal error: Oops - BUG: 0 [#1] PREEMPT SMP
Modules linked in:...
Process poc (pid: 5614, stack limit = 0x00000000a3933121)
CPU: 4 PID: 5614 Comm: poc Tainted: G S      W  O    4.14.180-g051355490483
Hardware name: Qualcomm Technologies, Inc. SM8150 V2 PM8150 Google Inc. MSM
task: 000000002a3dfffe task.stack: 00000000a3933121
pc : __cfi_check_fail+0x1c/0x24
lr : __cfi_check_fail+0x1c/0x24
...
Call trace:
__cfi_check_fail+0x1c/0x24
name_to_dev_t+0x0/0x468
nfnetlink_parse_nat_setup+0x234/0x258
ctnetlink_parse_nat_setup+0x4c/0x228
ctnetlink_new_conntrack+0x590/0xc40
nfnetlink_rcv_msg+0x31c/0x4d4
netlink_rcv_skb+0x100/0x184
nfnetlink_rcv+0xf4/0x180
netlink_unicast+0x360/0x770
netlink_sendmsg+0x5a0/0x6a4
___sys_sendmsg+0x314/0x46c
SyS_sendmsg+0xb4/0x108
el0_svc_naked+0x34/0x38

Fixes: c1d10adb4a521 ("[NETFILTER]: Add ctnetlink port for nf_conntrack")
Signed-off-by: Will McVicker <willmcvicker@google.com>
---
 net/netfilter/nf_conntrack_netlink.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/net/netfilter/nf_conntrack_netlink.c b/net/netfilter/nf_conntrack_netlink.c
index 31fa94064a62..0b89609a6e9d 100644
--- a/net/netfilter/nf_conntrack_netlink.c
+++ b/net/netfilter/nf_conntrack_netlink.c
@@ -1129,6 +1129,8 @@ ctnetlink_parse_tuple(const struct nlattr * const cda[],
 	if (!tb[CTA_TUPLE_IP])
 		return -EINVAL;
 
+	if (l3num != NFPROTO_IPV4 && l3num != NFPROTO_IPV6)
+		return -EOPNOTSUPP;
 	tuple->src.l3num = l3num;
 
 	err = ctnetlink_parse_tuple_ip(tb[CTA_TUPLE_IP], tuple);
-- 
2.28.0.297.g1956fa8f8d-goog


  reply	other threads:[~2020-08-24 19:39 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20200727175720.4022402-1-willmcvicker@google.com>
     [not found] ` <20200727175720.4022402-2-willmcvicker@google.com>
2020-07-27 19:07   ` [PATCH 0/1] Netfilter OOB memory access security patch Will McVicker
2020-07-27 19:07     ` Will McVicker
2020-08-20  8:23       ` Greg KH
2020-08-24 17:52         ` William Mcvicker
2020-07-27 19:07     ` [PATCH 1/1] netfilter: nat: add range checks for access to nf_nat_l[34]protos[] Will McVicker
     [not found]   ` <20200729214607.GA30831@salvia>
     [not found]     ` <20200731002611.GA1035680@google.com>
     [not found]       ` <20200731175115.GA16982@salvia>
     [not found]         ` <20200731181633.GA1209076@google.com>
2020-08-03 18:31           ` [PATCH v2 1/1] netfilter: nat: add a range check for l3/l4 protonum William Mcvicker
2020-08-04 11:37             ` Pablo Neira Ayuso
2020-08-24 19:38               ` [PATCH v3 0/1] " Will McVicker
2020-08-24 19:38                 ` Will McVicker [this message]
2020-08-28 16:42                   ` [PATCH v3 1/1] " Pablo Neira Ayuso
2020-08-28 16:45                     ` Florian Westphal
2020-08-28 17:11                       ` Pablo Neira Ayuso
2020-09-01 15:36               ` [PATCH v2 " Will Deacon
2020-09-01 17:29                 ` William Mcvicker

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