From: Pan Bian Date: Wed, 6 Nov 2019 07:31:07 +0000 (+0800) Subject: drm/i915/gvt: fix dropping obj reference twice X-Git-Url: http://git.lede-project.org./?a=commitdiff_plain;h=41d931459b53e32c67a1f8838d1e6826a69ee745;p=openwrt%2Fstaging%2Fblogic.git 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: e546e281d33d ("drm/i915/gvt: Dmabuf support for GVT-g") Signed-off-by: Pan Bian Reviewed-by: Zhenyu Wang Signed-off-by: Zhenyu Wang --- 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: