Commit 41d93145 authored Nov 06, 2019 by Pan Bian Committed by Zhenyu Wang Nov 08, 2019

drm/i915/gvt: fix dropping obj reference twice



The reference count of obj will be decremented twice if error occurs
in dma_buf_fd(). Additionally, attempting to read the reference count of
obj after dropping reference may lead to a use after free bug. Here, we
drop obj's reference until it is not used.

Fixes: e546e281 ("drm/i915/gvt: Dmabuf support for GVT-g")
Signed-off-by: Pan Bian <bianpan2016@163.com>
Reviewed-by: Zhenyu Wang <zhenyuw@linux.intel.com>
Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>

parent ee2c5ef8

drivers/gpu/drm/i915/gvt/dmabuf.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -498,8 +498,6 @@ int intel_vgpu_get_dmabuf(struct intel_vgpu *vgpu, unsigned int dmabuf_id)
		goto out_free_gem;
		}

		i915_gem_object_put(obj);

		ret = dma_buf_fd(dmabuf, DRM_CLOEXEC \| DRM_RDWR);
		if (ret < 0) {
		gvt_vgpu_err("create dma-buf fd failed ret:%d\n", ret);
		@@ -524,6 +522,8 @@ int intel_vgpu_get_dmabuf(struct intel_vgpu *vgpu, unsigned int dmabuf_id)
		file_count(dmabuf->file),
		kref_read(&obj->base.refcount));

		i915_gem_object_put(obj);

		return dmabuf_fd;

		out_free_dmabuf:

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