s390/qdio: fix access to uninitialized qdio_q fields

commit e5218134 upstream.

Ever since CQ/QAOB support was added, calling qdio_free() straight after
qdio_alloc() results in qdio_release_memory() accessing uninitialized
memory (ie. q->u.out.use_cq and q->u.out.aobs). Followed by a
kmem_cache_free() on the random AOB addresses.

For older kernels that don't have 6e30c549, the same applies if
qdio_establish() fails in the DEV_STATE_ONLINE check.

While initializing q->u.out.use_cq would be enough to fix this
particular bug, the more future-proof change is to just zero-alloc the
whole struct.

Fixes: 104ea556 ("qdio: support asynchronous delivery of storage blocks")
Cc: <stable@vger.kernel.org> #v3.2+
Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/s390/cio/qdio_setup.c

@@ -140,7 +140,7 @@ static int __qdio_allocate_qs(struct qdio_q **irq_ptr_qs, int nr_queues)
 	int i;
 
 	for (i = 0; i < nr_queues; i++) {
-		q = kmem_cache_alloc(qdio_q_cache, GFP_KERNEL);
+		q = kmem_cache_zalloc(qdio_q_cache, GFP_KERNEL);
 		if (!q)
 			return -ENOMEM;