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Commit 02b2faaf authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

tcp: fix various issues for sockets morphing to listen state 



Dmitry Vyukov reported a divide by 0 triggered by syzkaller, exploiting
tcp_disconnect() path that was never really considered and/or used
before syzkaller ;)

I was not able to reproduce the bug, but it seems issues here are the
three possible actions that assumed they would never trigger on a
listener.

1) tcp_write_timer_handler
2) tcp_delack_timer_handler
3) MTU reduction

Only IPv6 MTU reduction was properly testing TCP_CLOSE and TCP_LISTEN
 states from tcp_v6_mtu_reduced()

Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Reported-by: default avatarDmitry Vyukov <dvyukov@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent b73d2da8

net/ipv4/tcp_ipv4.c

+5 −2
Original line number Diff line number Diff line
@@ -279,10 +279,13 @@ EXPORT_SYMBOL(tcp_v4_connect); 
 */

void tcp_v4_mtu_reduced(struct sock *sk)

{

	struct dst_entry *dst;

	struct inet_sock *inet = inet_sk(sk);

	u32 mtu = tcp_sk(sk)->mtu_info;

	struct dst_entry *dst;

	u32 mtu;



	if ((1 << sk->sk_state) & (TCPF_LISTEN | TCPF_CLOSE))

		return;

	mtu = tcp_sk(sk)->mtu_info;

	dst = inet_csk_update_pmtu(sk, mtu);

	if (!dst)

		return;

net/ipv4/tcp_timer.c

+4 −2
Original line number Diff line number Diff line
@@ -249,7 +249,8 @@ void tcp_delack_timer_handler(struct sock *sk) 


	sk_mem_reclaim_partial(sk);



	if (sk->sk_state == TCP_CLOSE || !(icsk->icsk_ack.pending & ICSK_ACK_TIMER))

	if (((1 << sk->sk_state) & (TCPF_CLOSE | TCPF_LISTEN)) ||

	    !(icsk->icsk_ack.pending & ICSK_ACK_TIMER))

		goto out;



	if (time_after(icsk->icsk_ack.timeout, jiffies)) {
@@ -552,7 +553,8 @@ void tcp_write_timer_handler(struct sock *sk) 
	struct inet_connection_sock *icsk = inet_csk(sk);

	int event;



	if (sk->sk_state == TCP_CLOSE || !icsk->icsk_pending)

	if (((1 << sk->sk_state) & (TCPF_CLOSE | TCPF_LISTEN)) ||

	    !icsk->icsk_pending)

		goto out;



	if (time_after(icsk->icsk_timeout, jiffies)) {