From: Will McVicker willmcvicker@google.com
commit 1cc5ef91d2ff94d2bf2de3b3585423e8a1051cb6 upstream.
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
This crash is not happening since 5.4+, however, ctnetlink still allows for creating entries with unsupported layer 3 protocol number.
Fixes: c1d10adb4a521 ("[NETFILTER]: Add ctnetlink port for nf_conntrack") Signed-off-by: Will McVicker willmcvicker@google.com [pablo@netfilter.org: rebased original patch on top of nf.git] Signed-off-by: Pablo Neira Ayuso pablo@netfilter.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- net/netfilter/nf_conntrack_netlink.c | 2 ++ 1 file changed, 2 insertions(+)
--- a/net/netfilter/nf_conntrack_netlink.c +++ b/net/netfilter/nf_conntrack_netlink.c @@ -1031,6 +1031,8 @@ ctnetlink_parse_tuple(const struct nlatt 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);