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Subject: Re: [PATCH] drm/msm: prevent NULL dereference in
 msm_gpu_crashstate_capture()
To:     Tim Gardner <tim.gardner@canonical.com>,
        dri-devel@lists.freedesktop.org
Cc:     Rob Clark <robdclark@gmail.com>, Sean Paul <sean@poorly.run>,
        David Airlie <airlied@linux.ie>,
        Daniel Vetter <daniel@ffwll.ch>, linux-arm-msm@vger.kernel.org,
        freedreno@lists.freedesktop.org, linux-kernel@vger.kernel.org
References: <20210929162554.14295-1-tim.gardner@canonical.com>
From:   Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Message-ID: <7d251b1c-1054-6fde-602f-35eed4ac1cfe@linaro.org>
Date:   Sat, 2 Oct 2021 01:42:06 +0300
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On 29/09/2021 19:25, Tim Gardner wrote:
> Coverity complains of a possible NULL dereference:
> 
> CID 120718 (#1 of 1): Dereference null return value (NULL_RETURNS)
> 23. dereference: Dereferencing a pointer that might be NULL state->bos when
>      calling msm_gpu_crashstate_get_bo. [show details]
> 301                        msm_gpu_crashstate_get_bo(state, submit->bos[i].obj,
> 302                                submit->bos[i].iova, submit->bos[i].flags);
> 
> Fix this by employing the same state->bos NULL check as is used in the next
> for loop.
> 
> Cc: Rob Clark <robdclark@gmail.com>
> Cc: Sean Paul <sean@poorly.run>
> Cc: David Airlie <airlied@linux.ie>
> Cc: Daniel Vetter <daniel@ffwll.ch>
> Cc: linux-arm-msm@vger.kernel.org
> Cc: dri-devel@lists.freedesktop.org
> Cc: freedreno@lists.freedesktop.org
> Cc: linux-kernel@vger.kernel.org
> Signed-off-by: Tim Gardner <tim.gardner@canonical.com>

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>

> ---
>   drivers/gpu/drm/msm/msm_gpu.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/msm/msm_gpu.c b/drivers/gpu/drm/msm/msm_gpu.c
> index 8a3a592da3a4..2c46cd968ac4 100644
> --- a/drivers/gpu/drm/msm/msm_gpu.c
> +++ b/drivers/gpu/drm/msm/msm_gpu.c
> @@ -296,7 +296,7 @@ static void msm_gpu_crashstate_capture(struct msm_gpu *gpu,
>   		state->bos = kcalloc(nr,
>   			sizeof(struct msm_gpu_state_bo), GFP_KERNEL);
>   
> -		for (i = 0; i < submit->nr_bos; i++) {
> +		for (i = 0; state->bos && i < submit->nr_bos; i++) {
>   			if (should_dump(submit, i)) {
>   				msm_gpu_crashstate_get_bo(state, submit->bos[i].obj,
>   					submit->bos[i].iova, submit->bos[i].flags);
> 


-- 
With best wishes
Dmitry