From: David Riley Date: Wed, 5 Jun 2019 23:44:20 +0000 (-0700) Subject: drm/virtio: Ensure cached capset entries are valid before copying. X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=7fdf478a43869bee27e1b50955830f6ebc730b67;p=linux.git drm/virtio: Ensure cached capset entries are valid before copying. virtio_gpu_get_caps_ioctl could return success with invalid data if a second caller to the function occurred after the entry was created in virtio_gpu_cmd_get_capset but prior to the virtio_gpu_cmd_capset_cb callback being called. This could leak contents of memory as well since the caps_cache allocation is done without zeroing. Signed-off-by: David Riley Link: http://patchwork.freedesktop.org/patch/msgid/20190605234423.11348-1-davidriley@chromium.org Signed-off-by: Gerd Hoffmann --- diff --git a/drivers/gpu/drm/virtio/virtgpu_ioctl.c b/drivers/gpu/drm/virtio/virtgpu_ioctl.c index 8a17ef97aadaa..9f43b160e1bb7 100644 --- a/drivers/gpu/drm/virtio/virtgpu_ioctl.c +++ b/drivers/gpu/drm/virtio/virtgpu_ioctl.c @@ -524,7 +524,6 @@ static int virtio_gpu_get_caps_ioctl(struct drm_device *dev, list_for_each_entry(cache_ent, &vgdev->cap_cache, head) { if (cache_ent->id == args->cap_set_id && cache_ent->version == args->cap_set_ver) { - ptr = cache_ent->caps_cache; spin_unlock(&vgdev->display_info_lock); goto copy_exit; } @@ -535,6 +534,7 @@ static int virtio_gpu_get_caps_ioctl(struct drm_device *dev, virtio_gpu_cmd_get_capset(vgdev, found_valid, args->cap_set_ver, &cache_ent); +copy_exit: ret = wait_event_timeout(vgdev->resp_wq, atomic_read(&cache_ent->is_valid), 5 * HZ); if (!ret) @@ -542,7 +542,6 @@ static int virtio_gpu_get_caps_ioctl(struct drm_device *dev, ptr = cache_ent->caps_cache; -copy_exit: if (copy_to_user(u64_to_user_ptr(args->addr), ptr, size)) return -EFAULT;