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Message-ID: <39ee3606-6021-b4a8-12ec-c07b554e3b55@quicinc.com>
Date:   Thu, 22 Sep 2022 13:01:18 -0700
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Subject: Re: [Freedreno] [PATCH v2 01/10] drm/msm: fix use-after-free on probe
 deferral
Content-Language: en-US
To:     Johan Hovold <johan+linaro@kernel.org>,
        Douglas Anderson <dianders@chromium.org>,
        Dmitry Baryshkov <dmitry.baryshkov@linaro.org>,
        "Rob Clark" <robdclark@gmail.com>,
        Abhinav Kumar <quic_abhinavk@quicinc.com>
CC:     <dri-devel@lists.freedesktop.org>,
        Neil Armstrong <neil.armstrong@linaro.org>,
        Daniel Vetter <daniel@ffwll.ch>,
        Jonas Karlman <jonas@kwiboo.se>,
        <linux-arm-msm@vger.kernel.org>,
        Bjorn Andersson <andersson@kernel.org>,
        <freedreno@lists.freedesktop.org>, <linux-kernel@vger.kernel.org>,
        Jernej Skrabec <jernej.skrabec@gmail.com>,
        Stephen Boyd <swboyd@chromium.org>,
        Robert Foss <robert.foss@linaro.org>,
        Andrzej Hajda <andrzej.hajda@intel.com>,
        Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>,
        <stable@vger.kernel.org>, Sean Paul <sean@poorly.run>,
        Steev Klimaszewski <steev@kali.org>,
        Laurent Pinchart <Laurent.pinchart@ideasonboard.com>
References: <20220913085320.8577-1-johan+linaro@kernel.org>
 <20220913085320.8577-2-johan+linaro@kernel.org>
From:   Kuogee Hsieh <quic_khsieh@quicinc.com>
In-Reply-To: <20220913085320.8577-2-johan+linaro@kernel.org>
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On 9/13/2022 1:53 AM, Johan Hovold wrote:
> The bridge counter was never reset when tearing down the DRM device so
> that stale pointers to deallocated structures would be accessed on the
> next tear down (e.g. after a second late bind deferral).
>
> Given enough bridges and a few probe deferrals this could currently also
> lead to data beyond the bridge array being corrupted.
>
> Fixes: d28ea556267c ("drm/msm: properly add and remove internal bridges")
> Fixes: a3376e3ec81c ("drm/msm: convert to drm_bridge")
> Cc: stable@vger.kernel.org      # 3.12
> Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
> Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
Tested-by: Kuogee Hsieh <quic_khsieh@quicinc.com>
Reviewed-by: Kuogee Hsieh <quic_khsieh@quicinc.com>
> ---
>   drivers/gpu/drm/msm/msm_drv.c | 1 +
>   1 file changed, 1 insertion(+)
>
> diff --git a/drivers/gpu/drm/msm/msm_drv.c b/drivers/gpu/drm/msm/msm_drv.c
> index 391d86b54ded..d254fe2507ec 100644
> --- a/drivers/gpu/drm/msm/msm_drv.c
> +++ b/drivers/gpu/drm/msm/msm_drv.c
> @@ -241,6 +241,7 @@ static int msm_drm_uninit(struct device *dev)
>   
>   	for (i = 0; i < priv->num_bridges; i++)
>   		drm_bridge_remove(priv->bridges[i]);
> +	priv->num_bridges = 0;
>   
>   	pm_runtime_get_sync(dev);
>   	msm_irq_uninstall(ddev);