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Commit 19ec87d0 authored by Rob Clark's avatar Rob Clark Committed by Greg Kroah-Hartman
Browse files

drm/virtio: Fix GEM handle creation UAF 



[ Upstream commit 52531258318ed59a2dc5a43df2eaf0eb1d65438e ]

Userspace can guess the handle value and try to race GEM object creation
with handle close, resulting in a use-after-free if we dereference the
object after dropping the handle's reference.  For that reason, dropping
the handle's reference must be done *after* we are done dereferencing
the object.

Signed-off-by: default avatarRob Clark <robdclark@chromium.org>
Reviewed-by: default avatarChia-I Wu <olvaffe@gmail.com>
Fixes: 62fb7a5e ("virtio-gpu: add 3d/virgl support")
Cc: stable@vger.kernel.org
Signed-off-by: default avatarDmitry Osipenko <dmitry.osipenko@collabora.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20221216233355.542197-2-robdclark@gmail.com


Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent 34606ad2

drivers/gpu/drm/virtio/virtgpu_ioctl.c

+9 −1
Original line number Diff line number Diff line
@@ -309,7 +309,6 @@ static int virtio_gpu_resource_create_ioctl(struct drm_device *dev, void *data, 
		}

		return ret;

	}

	drm_gem_object_put_unlocked(obj);



	rc->res_handle = res_id; /* similiar to a VM address */

	rc->bo_handle = handle;
@@ -318,6 +317,15 @@ static int virtio_gpu_resource_create_ioctl(struct drm_device *dev, void *data, 
		virtio_gpu_unref_list(&validate_list);

		dma_fence_put(&fence->f);

	}



	/*

	 * The handle owns the reference now.  But we must drop our

	 * remaining reference *after* we no longer need to dereference

	 * the obj.  Otherwise userspace could guess the handle and

	 * race closing it from another thread.

	 */

	drm_gem_object_put_unlocked(obj);



	return 0;

fail_unref:

	if (vgdev->has_virgl_3d) {