smb: smbdirect: destroy QP before mem pools on accept failure

In the Linux kernel, the following vulnerability has been resolved: smb: smbdirect: destroy QP before mem pools on accept failure On the rdma_accept_failed error path of smbdirect_accept_connect_request(), the receive io posted just above is owned by the QP (recv_io is set to NULL after a successful post). The error path fell through to smbdirect_connection_destroy_mem_pools() before smbdirect_connection_destroy_qp(), so the mem pools and the recv_io slab cache were destroyed while that recv_io was still outstanding on the QP. The drain in smbdirect_connection_destroy_qp() (ib_drain_qp()) is what runs the recv completion that returns the recv_io to the free list, so destroying the pools first leaves the object outstanding at kmem_cache_destroy() time ("Slab cache still has objects") and later frees it into an already-destroyed mempool (mempool_free_bulk NULL-pointer dereference). Give rdma_accept_failed its own teardown that drains the QP first, then destroys the mem pools, and returns. The remaining labels (post_recv_io_failed onward) run before the recv_io was ever posted, so they keep the mem-pools-then-qp order. The outstanding recv_io at kmem_cache_destroy() time: [ 3487.344647] ============================================================================= [ 3487.349942] BUG smbdirect_recv_io_cache_ffff88811ba99000 (Not tainted): Objects remaining on __kmem_cache_shutdown() [ 3487.356078] ----------------------------------------------------------------------------- [ 3487