Re: [PATCH v3 1/1] netfilter: nat: add a range check for l3/l4 protonum
From: Pablo Neira Ayuso <pablo@netfilter.org>
Date: 2020-08-28 16:42:42
Also in:
lkml, netfilter-devel, stable
Hi Will, Given this is for -stable maintainers only, I'd suggest: 1) Specify what -stable kernel versions this patch applies to. Explain that this problem is gone since what kernel version. 2) Maybe clarify that this is only for stable in the patch subject, e.g. [PATCH -stable v3] netfilter: nat: add a range check for l3/l4 Otherwise, this -stable maintainers might not identify this patch as something that is targetted to them. Thanks. On Mon, Aug 24, 2020 at 07:38:32PM +0000, Will McVicker wrote:
quoted hunk ↗ jump to hunk
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 <redacted> --- 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