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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: e546e281d3 ("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>
This commit is contained in:
Pan Bian 2019-11-06 15:31:07 +08:00 committed by Zhenyu Wang
parent ee2c5ef8a9
commit 41d931459b
1 changed files with 2 additions and 2 deletions
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4
drivers/gpu/drm/i915/gvt/dmabuf.c
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@ -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: