From: Doug Horn <doughorn@xxxxxxxxxx> [ Upstream commit e219688fc5c3d0d9136f8d29d7e0498388f01440 ] 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. Signed-off-by: Doug Horn <doughorn@xxxxxxxxxx> Link: http://patchwork.freedesktop.org/patch/msgid/20200902210847.2689-2-gurchetansingh@xxxxxxxxxxxx Signed-off-by: Gerd Hoffmann <kraxel@xxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- drivers/gpu/drm/virtio/virtgpu_kms.c | 2 ++ drivers/gpu/drm/virtio/virtgpu_vq.c | 10 +++++++--- 2 files changed, 9 insertions(+), 3 deletions(-) diff --git a/drivers/gpu/drm/virtio/virtgpu_kms.c b/drivers/gpu/drm/virtio/virtgpu_kms.c index 65060c08522d7..22397a23780c0 100644 --- a/drivers/gpu/drm/virtio/virtgpu_kms.c +++ b/drivers/gpu/drm/virtio/virtgpu_kms.c @@ -113,8 +113,10 @@ static void virtio_gpu_get_capsets(struct virtio_gpu_device *vgdev, 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/drivers/gpu/drm/virtio/virtgpu_vq.c b/drivers/gpu/drm/virtio/virtgpu_vq.c index 608906f06cedd..3e72c6dac0ffe 100644 --- a/drivers/gpu/drm/virtio/virtgpu_vq.c +++ b/drivers/gpu/drm/virtio/virtgpu_vq.c @@ -566,9 +566,13 @@ static void virtio_gpu_cmd_get_capset_info_cb(struct virtio_gpu_device *vgdev, 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); } -- 2.25.1
