From: Pablo Neira Ayuso pablo@netfilter.org
commit 8866df9264a34e675b4ee8a151db819b87cce2d3 upstream
Otherwise, we hit a NULL pointer deference since handlers always assume default timeout policy is passed.
netlink: 24 bytes leftover after parsing attributes in process `syz-executor2'. kasan: CONFIG_KASAN_INLINE enabled kasan: GPF could be caused by NULL-ptr deref or user memory access general protection fault: 0000 [#1] PREEMPT SMP KASAN CPU: 0 PID: 9575 Comm: syz-executor1 Not tainted 4.19.0+ #312 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:icmp_timeout_obj_to_nlattr+0x77/0x170 net/netfilter/nf_conntrack_proto_icmp.c:297
Fixes: c779e849608a ("netfilter: conntrack: remove get_timeout() indirection") Reported-by: Eric Dumazet eric.dumazet@gmail.com Signed-off-by: Pablo Neira Ayuso pablo@netfilter.org Signed-off-by: Zubin Mithra zsm@chromium.org --- Notes: * Syzkaller reported a general protection fault in icmp_timeout_obj_to_nlattri when fuzzing a 4.19 kernel. Call Trace: cttimeout_default_fill_info net/netfilter/nfnetlink_cttimeout.c:424 [inline] cttimeout_default_get+0x574/0x766 net/netfilter/nfnetlink_cttimeout.c:471 nfnetlink_rcv_msg+0x544/0x5bd net/netfilter/nfnetlink.c:228 netlink_rcv_skb+0x1cf/0x2a1 net/netlink/af_netlink.c:2454 nfnetlink_rcv+0x30f/0x34a net/netfilter/nfnetlink.c:560 netlink_unicast_kernel net/netlink/af_netlink.c:1317 [inline] netlink_unicast+0x3c5/0x4c3 net/netlink/af_netlink.c:1343 netlink_sendmsg+0x829/0x88e net/netlink/af_netlink.c:1908 sock_sendmsg_nosec+0x8c/0xad net/socket.c:621 sock_sendmsg+0x4f/0x60 net/socket.c:631 ___sys_sendmsg+0x4d6/0x63f net/socket.c:2116 __sys_sendmsg+0xee/0x17b net/socket.c:2154 do_syscall_64+0xf8/0x133 arch/x86/entry/common.c:291 entry_SYSCALL_64_after_hwframe+0x49/0xbe
* This patch resolves the following conflicts when applying to 4.19: - l3num is not used as an argument for cttimeout_default_fill_info() in 4.19 - nf_icmp_pernet, nf_tcp_pernet, nf_udp_pernet, nf_dccp_pernet, nf_icmpv6_pernet, nf_sctp_pernet, nf_generic_pernet do not exist in 4.19. Expand the usage of those functions into one-liners.
* Tests run: Chrome OS tryjobs, Syzkaller reproducer
net/netfilter/nfnetlink_cttimeout.c | 46 +++++++++++++++++++++++++---- 1 file changed, 40 insertions(+), 6 deletions(-)
diff --git a/net/netfilter/nfnetlink_cttimeout.c b/net/netfilter/nfnetlink_cttimeout.c index a30f8ba4b89a..1dc4ea327cbe 100644 --- a/net/netfilter/nfnetlink_cttimeout.c +++ b/net/netfilter/nfnetlink_cttimeout.c @@ -392,7 +392,8 @@ static int cttimeout_default_set(struct net *net, struct sock *ctnl, static int cttimeout_default_fill_info(struct net *net, struct sk_buff *skb, u32 portid, u32 seq, u32 type, int event, - const struct nf_conntrack_l4proto *l4proto) + const struct nf_conntrack_l4proto *l4proto, + const unsigned int *timeouts) { struct nlmsghdr *nlh; struct nfgenmsg *nfmsg; @@ -421,7 +422,7 @@ cttimeout_default_fill_info(struct net *net, struct sk_buff *skb, u32 portid, if (!nest_parms) goto nla_put_failure;
- ret = l4proto->ctnl_timeout.obj_to_nlattr(skb, NULL); + ret = l4proto->ctnl_timeout.obj_to_nlattr(skb, timeouts); if (ret < 0) goto nla_put_failure;
@@ -444,6 +445,7 @@ static int cttimeout_default_get(struct net *net, struct sock *ctnl, struct netlink_ext_ack *extack) { const struct nf_conntrack_l4proto *l4proto; + unsigned int *timeouts = NULL; struct sk_buff *skb2; int ret, err; __u16 l3num; @@ -456,12 +458,44 @@ static int cttimeout_default_get(struct net *net, struct sock *ctnl, l4num = nla_get_u8(cda[CTA_TIMEOUT_L4PROTO]); l4proto = nf_ct_l4proto_find_get(l3num, l4num);
- /* This protocol is not supported, skip. */ - if (l4proto->l4proto != l4num) { - err = -EOPNOTSUPP; + err = -EOPNOTSUPP; + if (l4proto->l4proto != l4num) goto err; + + switch (l4proto->l4proto) { + case IPPROTO_ICMP: + timeouts = &net->ct.nf_ct_proto.icmp.timeout; + break; + case IPPROTO_TCP: + timeouts = net->ct.nf_ct_proto.tcp.timeouts; + break; + case IPPROTO_UDP: + timeouts = net->ct.nf_ct_proto.udp.timeouts; + break; + case IPPROTO_DCCP: +#ifdef CONFIG_NF_CT_PROTO_DCCP + timeouts = net->ct.nf_ct_proto.dccp.dccp_timeout; +#endif + break; + case IPPROTO_ICMPV6: + timeouts = &net->ct.nf_ct_proto.icmpv6.timeout; + break; + case IPPROTO_SCTP: +#ifdef CONFIG_NF_CT_PROTO_SCTP + timeouts = net->ct.nf_ct_proto.sctp.timeouts; +#endif + break; + case 255: + timeouts = &net->ct.nf_ct_proto.generic.timeout; + break; + default: + WARN_ON_ONCE(1); + break; }
+ if (!timeouts) + goto err; + skb2 = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL); if (skb2 == NULL) { err = -ENOMEM; @@ -472,7 +506,7 @@ static int cttimeout_default_get(struct net *net, struct sock *ctnl, nlh->nlmsg_seq, NFNL_MSG_TYPE(nlh->nlmsg_type), IPCTNL_MSG_TIMEOUT_DEFAULT_SET, - l4proto); + l4proto, timeouts); if (ret <= 0) { kfree_skb(skb2); err = -ENOMEM;