Commit 0f85feae authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
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tcp: fix more NULL deref after prequeue changes 



When I cooked commit c3658e8d ("tcp: fix possible NULL dereference in
tcp_vX_send_reset()") I missed other spots we could deref a NULL
skb_dst(skb)

Again, if a socket is provided, we do not need skb_dst() to get a
pointer to network namespace : sock_net(sk) is good enough.

Reported-by: default avatarDann Frazier <dann.frazier@canonical.com>
Bisected-by: default avatarDann Frazier <dann.frazier@canonical.com>
Tested-by: default avatarDann Frazier <dann.frazier@canonical.com>
Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Fixes: ca777eff ("tcp: remove dst refcount false sharing for prequeue mode")
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent f15650b7

net/ipv4/tcp_ipv4.c

+2 −2
Original line number Diff line number Diff line
@@ -623,6 +623,7 @@ static void tcp_v4_send_reset(struct sock *sk, struct sk_buff *skb) 
	arg.iov[0].iov_base = (unsigned char *)&rep;

	arg.iov[0].iov_len  = sizeof(rep.th);



	net = sk ? sock_net(sk) : dev_net(skb_dst(skb)->dev);

#ifdef CONFIG_TCP_MD5SIG

	hash_location = tcp_parse_md5sig_option(th);

	if (!sk && hash_location) {
@@ -633,7 +634,7 @@ static void tcp_v4_send_reset(struct sock *sk, struct sk_buff *skb) 
		 * Incoming packet is checked with md5 hash with finding key,

		 * no RST generated if md5 hash doesn't match.

		 */

		sk1 = __inet_lookup_listener(dev_net(skb_dst(skb)->dev),

		sk1 = __inet_lookup_listener(net,

					     &tcp_hashinfo, ip_hdr(skb)->saddr,

					     th->source, ip_hdr(skb)->daddr,

					     ntohs(th->source), inet_iif(skb));
@@ -681,7 +682,6 @@ static void tcp_v4_send_reset(struct sock *sk, struct sk_buff *skb) 
	if (sk)

		arg.bound_dev_if = sk->sk_bound_dev_if;



	net = dev_net(skb_dst(skb)->dev);

	arg.tos = ip_hdr(skb)->tos;

	ip_send_unicast_reply(net, skb, &TCP_SKB_CB(skb)->header.h4.opt,

			      ip_hdr(skb)->saddr, ip_hdr(skb)->daddr,

net/ipv6/tcp_ipv6.c

+14 −14
Original line number Diff line number Diff line
@@ -787,16 +787,16 @@ static const struct tcp_request_sock_ops tcp_request_sock_ipv6_ops = { 
	.queue_hash_add =	inet6_csk_reqsk_queue_hash_add,

};



static void tcp_v6_send_response(struct sk_buff *skb, u32 seq, u32 ack, u32 win,

				 u32 tsval, u32 tsecr, int oif,

				 struct tcp_md5sig_key *key, int rst, u8 tclass,

				 u32 label)

static void tcp_v6_send_response(struct sock *sk, struct sk_buff *skb, u32 seq,

				 u32 ack, u32 win, u32 tsval, u32 tsecr,

				 int oif, struct tcp_md5sig_key *key, int rst,

				 u8 tclass, u32 label)

{

	const struct tcphdr *th = tcp_hdr(skb);

	struct tcphdr *t1;

	struct sk_buff *buff;

	struct flowi6 fl6;

	struct net *net = dev_net(skb_dst(skb)->dev);

	struct net *net = sk ? sock_net(sk) : dev_net(skb_dst(skb)->dev);

	struct sock *ctl_sk = net->ipv6.tcp_sk;

	unsigned int tot_len = sizeof(struct tcphdr);

	struct dst_entry *dst;
@@ -946,7 +946,7 @@ static void tcp_v6_send_reset(struct sock *sk, struct sk_buff *skb) 
			  (th->doff << 2);



	oif = sk ? sk->sk_bound_dev_if : 0;

	tcp_v6_send_response(skb, seq, ack_seq, 0, 0, 0, oif, key, 1, 0, 0);

	tcp_v6_send_response(sk, skb, seq, ack_seq, 0, 0, 0, oif, key, 1, 0, 0);



#ifdef CONFIG_TCP_MD5SIG

release_sk1:
@@ -957,13 +957,13 @@ release_sk1: 
#endif

}



static void tcp_v6_send_ack(struct sk_buff *skb, u32 seq, u32 ack,

			    u32 win, u32 tsval, u32 tsecr, int oif,

static void tcp_v6_send_ack(struct sock *sk, struct sk_buff *skb, u32 seq,

			    u32 ack, u32 win, u32 tsval, u32 tsecr, int oif,

			    struct tcp_md5sig_key *key, u8 tclass,

			    u32 label)

{

	tcp_v6_send_response(skb, seq, ack, win, tsval, tsecr, oif, key, 0, tclass,

			     label);

	tcp_v6_send_response(sk, skb, seq, ack, win, tsval, tsecr, oif, key, 0,

			     tclass, label);

}



static void tcp_v6_timewait_ack(struct sock *sk, struct sk_buff *skb)
@@ -971,7 +971,7 @@ static void tcp_v6_timewait_ack(struct sock *sk, struct sk_buff *skb) 
	struct inet_timewait_sock *tw = inet_twsk(sk);

	struct tcp_timewait_sock *tcptw = tcp_twsk(sk);



	tcp_v6_send_ack(skb, tcptw->tw_snd_nxt, tcptw->tw_rcv_nxt,

	tcp_v6_send_ack(sk, skb, tcptw->tw_snd_nxt, tcptw->tw_rcv_nxt,

			tcptw->tw_rcv_wnd >> tw->tw_rcv_wscale,

			tcp_time_stamp + tcptw->tw_ts_offset,

			tcptw->tw_ts_recent, tw->tw_bound_dev_if, tcp_twsk_md5_key(tcptw),
@@ -986,10 +986,10 @@ static void tcp_v6_reqsk_send_ack(struct sock *sk, struct sk_buff *skb, 
	/* sk->sk_state == TCP_LISTEN -> for regular TCP_SYN_RECV

	 * sk->sk_state == TCP_SYN_RECV -> for Fast Open.

	 */

	tcp_v6_send_ack(skb, (sk->sk_state == TCP_LISTEN) ?

	tcp_v6_send_ack(sk, skb, (sk->sk_state == TCP_LISTEN) ?

			tcp_rsk(req)->snt_isn + 1 : tcp_sk(sk)->snd_nxt,

			tcp_rsk(req)->rcv_nxt,

			req->rcv_wnd, tcp_time_stamp, req->ts_recent, sk->sk_bound_dev_if,

			tcp_rsk(req)->rcv_nxt, req->rcv_wnd,

			tcp_time_stamp, req->ts_recent, sk->sk_bound_dev_if,

			tcp_v6_md5_do_lookup(sk, &ipv6_hdr(skb)->daddr),

			0, 0);

}

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