pvrdma: Fix the ring init error flow (CVE-2021-3608)

Do not unmap uninitialized dma addresses.

Fixes: CVE-2021-3608
Reviewed-by: VictorV (Kunlun Lab) <vv474172261@gmail.com>
Tested-by: VictorV (Kunlun Lab) <vv474172261@gmail.com>
Signed-off-by: Marcel Apfelbaum <marcel@redhat.com>
Message-Id: <20210630115246.2178219-1-marcel@redhat.com>
Tested-by: Yuval Shaia <yuval.shaia.ml@gmail.com>
Reviewed-by: Yuval Shaia <yuval.shaia.ml@gmail.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: Marcel Apfelbaum <marcel.apfelbaum@gmail.com>

hw/rdma/vmw/pvrdma_dev_ring.c

@@ -41,7 +41,7 @@ int pvrdma_ring_init(PvrdmaRing *ring, const char *name, PCIDevice *dev,
     qatomic_set(&ring->ring_state->cons_head, 0);
     */
     ring->npages = npages;
-    ring->pages = g_malloc(npages * sizeof(void *));
+    ring->pages = g_malloc0(npages * sizeof(void *));
 
     for (i = 0; i < npages; i++) {
         if (!tbl[i]) {