net/smc: fix connection leak

In the Linux kernel, the following vulnerability has been resolved:

net/smc: fix connection leak

There's a potential leak issue under following execution sequence :

smc_release smc_connect_work

if (sk->sk_state == SMC_INIT)

send_clc_confirim

tcp_abort();

...

sk.sk_state = SMC_ACTIVE

smc_close_active

switch(sk->sk_state) {

...

case SMC_ACTIVE:

smc_close_final()

// then wait peer closed

Unfortunately, tcp_abort() may discard CLC CONFIRM messages that are

still in the tcp send buffer, in which case our connection token cannot

be delivered to the server side, which means that we cannot get a

passive close message at all. Therefore, it is impossible for the to be

disconnected at all.

This patch tries a very simple way to avoid this issue, once the state

has changed to SMC_ACTIVE after tcp_abort(), we can actively abort the

smc connection, considering that the state is SMC_INIT before

tcp_abort(), abandoning the complete disconnection process should not

cause too much problem.

In fact, this problem may exist as long as the CLC CONFIRM message is

not received by the server. Whether a timer should be added after

smc_close_final() needs to be discussed in the future. But even so, this

patch provides a faster release for connection in above case, it should

also be valuable.