drm/virtio: Ensure that objs is not NULL in virtio_gpu_array_put_free()

commit 6b79f96f4a23846516e5e6e4dd37fc06f43a60dd upstream.

If virtio_gpu_object_shmem_init() fails (e.g. due to fault injection, as it
happened in the bug report by syzbot), virtio_gpu_array_put_free() could be
called with objs equal to NULL.

Ensure that objs is not NULL in virtio_gpu_array_put_free(), or otherwise
return from the function.

Cc: stable@vger.kernel.org # 5.13.x
Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
Reported-by: syzbot+e9072e90624a31dfa85f@syzkaller.appspotmail.com
Fixes: 377f8331d0565 ("drm/virtio: fix possible leak/unlock virtio_gpu_object_array")
Link: http://patchwork.freedesktop.org/patch/msgid/20211213183122.838119-1-roberto.sassu@huawei.com
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/gpu/drm/virtio/virtgpu_gem.c b/drivers/gpu/drm/virtio/virtgpu_gem.c
index 2de61b6..48d3c99 100644 (file)
--- a/drivers/gpu/drm/virtio/virtgpu_gem.c
+++ b/drivers/gpu/drm/virtio/virtgpu_gem.c
@@ -248,6 +248,9 @@ void virtio_gpu_array_put_free(struct virtio_gpu_object_array *objs)
 {
        u32 i;
 
+       if (!objs)
+               return;
+
        for (i = 0; i < objs->nents; i++)
                drm_gem_object_put(objs->objs[i]);
        virtio_gpu_array_free(objs);