CVE-2026-46158

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

mptcp: pm: ADD_ADDR rtx: always decrease sk refcount

When an ADD_ADDR is retransmitted, the sk is held in sk_reset_timer().

It should then be released in all cases at the end.

Some (unlikely) checks were returning directly instead of calling

sock_put() to decrease the refcount. Jump to a new 'exit' label to call

__sock_put() (which will become sock_put() in the next commit) to fix

this potential leak.

While at it, drop the '!msk' check which cannot happen because it is

never reset, and explicitly mark the remaining one as "unlikely".