tipc: fix a potential oops
tipc: fix a potential oops

Commit 6c9808ce09f7 ("tipc: remove port_lock") accidentally involves
a potential bug: when tipc socket instance(tsk) is not got with given
reference number in tipc_sk_get(), tsk is set to NULL. Subsequently
we jump to exit label where to decrease socket reference counter
pointed by tsk pointer in tipc_sk_put(). However, As now tsk is NULL,
oops may happen because of touching a NULL pointer.

Signed-off-by: Ying Xue <c1cbb87de349443b90fa63f6d2cc5403843bc133@windriver.com>
Acked-by: Erik Hugne <527d9b95423f3946c01de0ba884fdd8bb4a3759d@ericsson.com>
Acked-by: Jon Maloy <0e60c7c02f6d30eccc82572d2a89766b1b2a3d45@ericsson.com>
Signed-off-by: David S. Miller <fe08d3c717adf2ae63592e4c9aec6e3e404d8e3e@davemloft.net>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs