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 <cpaa...@apple.com>
Fixes: 729cd6436f35 ("mptcp: cope better with MP_JOIN failure")
Signed-off-by: Paolo Abeni <pab...@redhat.com>
---
include/net/inet_connection_sock.h | 1 -
net/ipv4/inet_connection_sock.c | 1 +
2 files changed, 1 insertion(+), 1 deletion(-)
diff --git a/include/net/inet_connection_sock.h
b/include/net/inet_connection_sock.h
index 2f1f8c3efb26..e5b388f5fa20 100644
--- a/include/net/inet_connection_sock.h
+++ b/include/net/inet_connection_sock.h
@@ -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);
diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c
index f40b1b72f979..afaf582a5aa9 100644
--- a/net/ipv4/inet_connection_sock.c
+++ b/net/ipv4/inet_connection_sock.c
@@ -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);
--
2.21.3
