From: Eric Dumazet edumazet@google.com
This patch has been added to the stable tree. If you have any objections, please let us know.
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[ Upstream commit 02b2faaf0af1d85585f6d6980e286d53612acfc2 ]
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: Eric Dumazet edumazet@google.com Reported-by: Dmitry Vyukov dvyukov@google.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Sasha Levin alexander.levin@microsoft.com --- net/ipv4/tcp_ipv4.c | 7 +++++-- net/ipv4/tcp_timer.c | 6 ++++-- 2 files changed, 9 insertions(+), 4 deletions(-)
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c index 13b92d595138..23ea6cf1a4e5 100644 --- a/net/ipv4/tcp_ipv4.c +++ b/net/ipv4/tcp_ipv4.c @@ -271,10 +271,13 @@ 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; diff --git a/net/ipv4/tcp_timer.c b/net/ipv4/tcp_timer.c index c8f97858d6f6..f8c6b2343301 100644 --- a/net/ipv4/tcp_timer.c +++ b/net/ipv4/tcp_timer.c @@ -223,7 +223,8 @@ 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)) { @@ -504,7 +505,8 @@ 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)) {