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inet_connection_sock: clear inet_num out of destroy helper 

Clearing the 'inet_num' field is necessary and safe if and
only if the socket is not bound. The MPTCP protocol calls
the destroy helper on bound sockets, as tcp_v{4,6}_syn_recv_sock
completed successfully.

Move the clearing of such field out of the common code, otherwise
the MPTCP MP_JOIN error path will find the wrong 'inet_num' value
on socket disposal, __inet_put_port() will acquire the wrong lock
and bind_node removal could race with other modifiers possibly
corrupting the bind hash table.

Reported-and-tested-by: Christoph Paasch <cpaasch@apple.com>
Fixes: 729cd6436f ("mptcp: cope better with MP_JOIN failure")
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
alistair/sunxi64-5.8
Paolo Abeni 2020-06-04 18:55:45 +02:00 committed by David S. Miller
parent 98749b7188
commit 6761893eea
2 changed files with 1 additions and 1 deletions
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1
include/net/inet_connection_sock.h
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@ -292,7 +292,6 @@ static inline void inet_csk_prepare_for_destroy_sock(struct sock *sk)
/* The below has to be done to allow calling inet_csk_destroy_sock */
sock_set_flag(sk, SOCK_DEAD);
percpu_counter_inc(sk->sk_prot->orphan_count);
inet_sk(sk)->inet_num = 0;
}
void inet_csk_destroy_sock(struct sock *sk);

1
net/ipv4/inet_connection_sock.c
View File

@ -902,6 +902,7 @@ void inet_csk_prepare_forced_close(struct sock *sk)
bh_unlock_sock(sk);
sock_put(sk);
inet_csk_prepare_for_destroy_sock(sk);
inet_sk(sk)->inet_num = 0;
}
EXPORT_SYMBOL(inet_csk_prepare_forced_close);