Messages in this thread | | | Date | Wed, 6 Nov 2019 16:43:49 +0800 | From | Zhenyu Wang <> | Subject | Re: [PATCH] drm/i915/gvt: fix dropping obj reference twice |
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On 2019.11.06 15:31:07 +0800, Pan Bian wrote: > 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. > > Signed-off-by: Pan Bian <bianpan2016@163.com> > --- > drivers/gpu/drm/i915/gvt/dmabuf.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/gpu/drm/i915/gvt/dmabuf.c b/drivers/gpu/drm/i915/gvt/dmabuf.c > index 13044c027f27..4bfaefdf548d 100644 > --- a/drivers/gpu/drm/i915/gvt/dmabuf.c > +++ b/drivers/gpu/drm/i915/gvt/dmabuf.c > @@ -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:
Looks fine to me. Thanks!
Reviewed-by: Zhenyu Wang <zhenyuw@linux.intel.com>
-- Open Source Technology Center, Intel ltd.
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