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From: Zhenyu Wang <zhenyuw@linux.intel.com>
To: Pan Bian <bianpan2016@163.com>
Cc: Zhi Wang <zhi.a.wang@intel.com>,
	Jani Nikula <jani.nikula@linux.intel.com>,
	Joonas Lahtinen <joonas.lahtinen@linux.intel.com>,
	Rodrigo Vivi <rodrigo.vivi@intel.com>,
	David Airlie <airlied@linux.ie>, Daniel Vetter <daniel@ffwll.ch>,
	intel-gvt-dev@lists.freedesktop.org,
	intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH] drm/i915/gvt: fix dropping obj reference twice
Date: Wed, 6 Nov 2019 16:43:49 +0800	[thread overview]
Message-ID: <20191106084349.GB4196@zhen-hp.sh.intel.com> (raw)
In-Reply-To: <1573025467-18278-1-git-send-email-bianpan2016@163.com>

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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.

$gpg --keyserver wwwkeys.pgp.net --recv-keys 4D781827

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WARNING: multiple messages have this Message-ID (diff)
From: Zhenyu Wang <zhenyuw@linux.intel.com>
To: Pan Bian <bianpan2016@163.com>
Cc: David Airlie <airlied@linux.ie>,
	intel-gfx@lists.freedesktop.org, linux-kernel@vger.kernel.org,
	dri-devel@lists.freedesktop.org,
	Rodrigo Vivi <rodrigo.vivi@intel.com>,
	intel-gvt-dev@lists.freedesktop.org,
	Zhi Wang <zhi.a.wang@intel.com>
Subject: Re: [PATCH] drm/i915/gvt: fix dropping obj reference twice
Date: Wed, 6 Nov 2019 16:43:49 +0800	[thread overview]
Message-ID: <20191106084349.GB4196@zhen-hp.sh.intel.com> (raw)
Message-ID: <20191106084349.0_kDPUk4aOJAMPdiwUQnhHI5rvNzZjqXB9TaZOz1F_U@z> (raw)
In-Reply-To: <1573025467-18278-1-git-send-email-bianpan2016@163.com>


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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.

$gpg --keyserver wwwkeys.pgp.net --recv-keys 4D781827

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_______________________________________________
dri-devel mailing list
dri-devel@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/dri-devel

WARNING: multiple messages have this Message-ID (diff)
From: Zhenyu Wang <zhenyuw@linux.intel.com>
To: Pan Bian <bianpan2016@163.com>
Cc: David Airlie <airlied@linux.ie>,
	intel-gfx@lists.freedesktop.org, linux-kernel@vger.kernel.org,
	dri-devel@lists.freedesktop.org,
	intel-gvt-dev@lists.freedesktop.org
Subject: Re: [Intel-gfx] [PATCH] drm/i915/gvt: fix dropping obj reference twice
Date: Wed, 6 Nov 2019 16:43:49 +0800	[thread overview]
Message-ID: <20191106084349.GB4196@zhen-hp.sh.intel.com> (raw)
Message-ID: <20191106084349.5Aut6abJzcmufeIxtOVCczQ3iSbQVLEM5hXyA52AMXE@z> (raw)
In-Reply-To: <1573025467-18278-1-git-send-email-bianpan2016@163.com>


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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.

$gpg --keyserver wwwkeys.pgp.net --recv-keys 4D781827

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_______________________________________________
Intel-gfx mailing list
Intel-gfx@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/intel-gfx

  reply	other threads:[~2019-11-06  8:44 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-11-06  7:31 [PATCH] drm/i915/gvt: fix dropping obj reference twice Pan Bian
2019-11-06  7:31 ` [Intel-gfx] " Pan Bian
2019-11-06  7:31 ` Pan Bian
2019-11-06  8:43 ` Zhenyu Wang [this message]
2019-11-06  8:43   ` [Intel-gfx] " Zhenyu Wang
2019-11-06  8:43   ` Zhenyu Wang
2019-11-06 22:27 ` ✓ Fi.CI.BAT: success for " Patchwork
2019-11-06 22:27   ` [Intel-gfx] " Patchwork
2019-11-08  0:02 ` ✓ Fi.CI.IGT: " Patchwork
2019-11-08  0:02   ` [Intel-gfx] " Patchwork

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