FROMGIT: drm/virtio: Fix use after free in get_capset_info callback.
If a response to virtio_gpu_cmd_get_capset_info takes longer than
five seconds to return, the callback will access freed kernel memory
in vg->capsets.
Bug: 166299146
Signed-off-by: Doug Horn <doughorn@google.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
(cherry picked from commit e219688fc5c3d0d9136f8d29d7e0498388f01440)
Change-Id: I1ab01855152e12dc34c56f9c85d723c8e7f7780c
diff --git a/virtio_gpu/virtgpu_kms.c b/virtio_gpu/virtgpu_kms.c
index 01d6f62..88b16df 100644
--- a/virtio_gpu/virtgpu_kms.c
+++ b/virtio_gpu/virtgpu_kms.c
@@ -97,8 +97,10 @@
vgdev->capsets[i].id > 0, 5 * HZ);
if (ret == 0) {
DRM_ERROR("timed out waiting for cap set %d\n", i);
+ spin_lock(&vgdev->display_info_lock);
kfree(vgdev->capsets);
vgdev->capsets = NULL;
+ spin_unlock(&vgdev->display_info_lock);
return;
}
DRM_INFO("cap set %d: id %d, max-version %d, max-size %d\n",
diff --git a/virtio_gpu/virtgpu_vq.c b/virtio_gpu/virtgpu_vq.c
index 93b32ef..1b7f4e6 100644
--- a/virtio_gpu/virtgpu_vq.c
+++ b/virtio_gpu/virtgpu_vq.c
@@ -572,9 +572,13 @@
int i = le32_to_cpu(cmd->capset_index);
spin_lock(&vgdev->display_info_lock);
- vgdev->capsets[i].id = le32_to_cpu(resp->capset_id);
- vgdev->capsets[i].max_version = le32_to_cpu(resp->capset_max_version);
- vgdev->capsets[i].max_size = le32_to_cpu(resp->capset_max_size);
+ if (vgdev->capsets) {
+ vgdev->capsets[i].id = le32_to_cpu(resp->capset_id);
+ vgdev->capsets[i].max_version = le32_to_cpu(resp->capset_max_version);
+ vgdev->capsets[i].max_size = le32_to_cpu(resp->capset_max_size);
+ } else {
+ DRM_ERROR("invalid capset memory.");
+ }
spin_unlock(&vgdev->display_info_lock);
wake_up(&vgdev->resp_wq);
}
