[PATCH] virtio/vhost-user: Fix wrong vhost notifier GPtrArray size

[Yajun Wu <yajunw@nvidia.com>]

In fetch_or_create_notifier, idx begins with 0. So the GPtrArray size
should be idx + 1 and g_ptr_array_set_size should be called with idx + 1.

This wrong GPtrArray size causes fetch_or_create_notifier return an invalid
address. Passing this invalid pointer to vhost_user_host_notifier_remove
causes assert fail:

    qemu/include/qemu/int128.h:27: int128_get64: Assertion `r == a' failed.
	shutting down, reason=crashed

Backends like dpdk-vdpa which sends out vhost notifier requests almost always
hit qemu crash.

Fixes: 503e355465 ("virtio/vhost-user: dynamically assign VhostUserHostNotifiers")
Signed-off-by: Yajun Wu <yajunw@nvidia.com>
Acked-by: Parav Pandit <parav@nvidia.com>
Change-Id: I87e0f7591ca9a59d210879b260704a2d9e9d6bcd
---
 hw/virtio/vhost-user.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c
index b040c1ad2b..dbc690d16c 100644
--- a/hw/virtio/vhost-user.c
+++ b/hw/virtio/vhost-user.c
@@ -1525,7 +1525,7 @@ static VhostUserHostNotifier *fetch_or_create_notifier(VhostUserState *u,
 {
     VhostUserHostNotifier *n = NULL;
     if (idx >= u->notifiers->len) {
-        g_ptr_array_set_size(u->notifiers, idx);
+        g_ptr_array_set_size(u->notifiers, idx + 1);
     }
 
     n = g_ptr_array_index(u->notifiers, idx);
-- 
2.36.0