On Wed, Nov 16, 2022 at 2:28 PM Kuniyuki Iwashima <kuniyu@xxxxxxxxxx> wrote:
>
> When connect() is called on a socket bound to the wildcard address,
> we change the socket's saddr to a local address. If the socket
> fails to connect() to the destination, we have to reset the saddr.
>
> However, when an error occurs after inet_hash6?_connect() in
> (dccp|tcp)_v[46]_conect(), we forget to reset saddr and leave
> the socket bound to the address.
>
> From the user's point of view, whether saddr is reset or not varies
> with errno. Let's fix this inconsistent behaviour.
>
> Note that after this patch, the repro [0] will trigger the WARN_ON()
> in inet_csk_get_port() again, but this patch is not buggy and rather
> fixes a bug papering over the bhash2's bug for which we need another
> fix.
>
> For the record, the repro causes -EADDRNOTAVAIL in inet_hash6_connect()
> by this sequence:
>
> s1 = socket()
> s1.setsockopt(SOL_SOCKET, SO_REUSEADDR, 1)
> s1.bind(('127.0.0.1', 10000))
> s1.sendto(b'hello', MSG_FASTOPEN, (('127.0.0.1', 10000)))
> # or s1.connect(('127.0.0.1', 10000))
>
> s2 = socket()
> s2.setsockopt(SOL_SOCKET, SO_REUSEADDR, 1)
> s2.bind(('0.0.0.0', 10000))
> s2.connect(('127.0.0.1', 10000)) # -EADDRNOTAVAIL
>
> s2.listen(32) # WARN_ON(inet_csk(sk)->icsk_bind2_hash != tb2);
>
> [0]: https://syzkaller.appspot.com/bug?extid=015d756bbd1f8b5c8f09
>
> Fixes: 3df80d9320bc ("[DCCP]: Introduce DCCPv6")
> Fixes: 7c657876b63c ("[DCCP]: Initial implementation")
> Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
> Signed-off-by: Kuniyuki Iwashima <kuniyu@xxxxxxxxxx>
LGTM. Btw, the 4th patch in this series overwrites these changes by
moving this logic into the new inet_bhash2_reset_saddr() function you
added, so we could also drop this patch from the series. OTOH, this
commit message in this patch has some good background context. So I
don't have a preference either way :)
Acked-by: Joanne Koong <joannelkoong@xxxxxxxxx>
> ---
> net/dccp/ipv4.c | 2 ++
> net/dccp/ipv6.c | 2 ++
> net/ipv4/tcp_ipv4.c | 2 ++
> net/ipv6/tcp_ipv6.c | 2 ++
> 4 files changed, 8 insertions(+)
>
> diff --git a/net/dccp/ipv4.c b/net/dccp/ipv4.c
> index 713b7b8dad7e..40640c26680e 100644
> --- a/net/dccp/ipv4.c
> +++ b/net/dccp/ipv4.c
> @@ -157,6 +157,8 @@ int dccp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
> * This unhashes the socket and releases the local port, if necessary.
> */
> dccp_set_state(sk, DCCP_CLOSED);
> + if (!(sk->sk_userlocks & SOCK_BINDADDR_LOCK))
> + inet_reset_saddr(sk);
> ip_rt_put(rt);
> sk->sk_route_caps = 0;
> inet->inet_dport = 0;
> diff --git a/net/dccp/ipv6.c b/net/dccp/ipv6.c
> index e57b43006074..626166cb6d7e 100644
> --- a/net/dccp/ipv6.c
> +++ b/net/dccp/ipv6.c
> @@ -985,6 +985,8 @@ static int dccp_v6_connect(struct sock *sk, struct sockaddr *uaddr,
>
> late_failure:
> dccp_set_state(sk, DCCP_CLOSED);
> + if (!(sk->sk_userlocks & SOCK_BINDADDR_LOCK))
> + inet_reset_saddr(sk);
> __sk_dst_reset(sk);
> failure:
> inet->inet_dport = 0;
> diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
> index 87d440f47a70..6a3a732b584d 100644
> --- a/net/ipv4/tcp_ipv4.c
> +++ b/net/ipv4/tcp_ipv4.c
> @@ -343,6 +343,8 @@ int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
> * if necessary.
> */
> tcp_set_state(sk, TCP_CLOSE);
> + if (!(sk->sk_userlocks & SOCK_BINDADDR_LOCK))
> + inet_reset_saddr(sk);
> ip_rt_put(rt);
> sk->sk_route_caps = 0;
> inet->inet_dport = 0;
> diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
> index 2a3f9296df1e..81b396e5cf79 100644
> --- a/net/ipv6/tcp_ipv6.c
> +++ b/net/ipv6/tcp_ipv6.c
> @@ -359,6 +359,8 @@ static int tcp_v6_connect(struct sock *sk, struct sockaddr *uaddr,
>
> late_failure:
> tcp_set_state(sk, TCP_CLOSE);
> + if (!(sk->sk_userlocks & SOCK_BINDADDR_LOCK))
> + inet_reset_saddr(sk);
> failure:
> inet->inet_dport = 0;
> sk->sk_route_caps = 0;
> --
> 2.30.2
>
