virtio: Allow .get_vhost() without vhost_started

Historically, .get_vhost() was probably only called when
vdev->vhost_started is true.  However, we now decidedly want to call it
also when vhost_started is false, specifically so we can issue a reset
to the vhost back-end while device operation is stopped.

Some .get_vhost() implementations dereference some pointers (or return
offsets from them) that are probably guaranteed to be non-NULL when
vhost_started is true, but not necessarily otherwise.  This patch makes
all such implementations check all such pointers, returning NULL if any
is NULL.

Signed-off-by: Hanna Czenczek <hreitz@redhat.com>
Message-Id: <20240723163941.48775-2-hreitz@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>

1 files changed, 15 insertions, 3 deletions

diff --git a/hw/virtio/virtio-crypto.c b/hw/virtio/virtio-crypto.c
index 5034768bff..0793f56965 100644
--- a/hw/virtio/virtio-crypto.c
+++ b/hw/virtio/virtio-crypto.c
@@ -1247,9 +1247,21 @@ static bool virtio_crypto_guest_notifier_pending(VirtIODevice *vdev, int idx)
 static struct vhost_dev *virtio_crypto_get_vhost(VirtIODevice *vdev)
 {
     VirtIOCrypto *vcrypto = VIRTIO_CRYPTO(vdev);
-    CryptoDevBackend *b = vcrypto->cryptodev;
-    CryptoDevBackendClient *cc = b->conf.peers.ccs[0];
-    CryptoDevBackendVhost *vhost_crypto = cryptodev_get_vhost(cc, b, 0);
+    CryptoDevBackend *b;
+    CryptoDevBackendClient *cc;
+    CryptoDevBackendVhost *vhost_crypto;
+
+    b = vcrypto->cryptodev;
+    if (!b) {
+        return NULL;
+    }
+
+    cc = b->conf.peers.ccs[0];
+    vhost_crypto = cryptodev_get_vhost(cc, b, 0);
+    if (!vhost_crypto) {
+        return NULL;
+    }
+
     return &vhost_crypto->dev;
 }