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Message-ID: <0b63ef49-7a59-0a72-503c-1de20a502c6a@linaro.org>
Date: Mon, 9 Jan 2023 00:08:08 +0200
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: Jiasheng Jiang <jiasheng@...as.ac.cn>, robdclark@...il.com,
quic_abhinavk@...cinc.com, sean@...rly.run, airlied@...il.com,
daniel@...ll.ch, quic_jesszhan@...cinc.com,
ville.syrjala@...ux.intel.com, yang.lee@...ux.alibaba.com
Cc: linux-arm-msm@...r.kernel.org, dri-devel@...ts.freedesktop.org,
freedreno@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] drm/msm/dpu: Add check for cstate
On 08/01/2023 23:56, Dmitry Baryshkov wrote:
> On 06/12/2022 10:05, Jiasheng Jiang wrote:
>> As kzalloc may fail and return NULL pointer,
>> it should be better to check cstate
>> in order to avoid the NULL pointer dereference
>> in __drm_atomic_helper_crtc_reset.
>>
>> Fixes: 1cff7440a86e ("drm/msm: Convert to using
>> __drm_atomic_helper_crtc_reset() for reset.")
>> Signed-off-by: Jiasheng Jiang <jiasheng@...as.ac.cn>
>> ---
>> drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c | 5 ++++-
>> 1 file changed, 4 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c
>> b/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c
>> index 13ce321283ff..22c2787b7b38 100644
>> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c
>> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c
>> @@ -968,7 +968,10 @@ static void dpu_crtc_reset(struct drm_crtc *crtc)
>> if (crtc->state)
>> dpu_crtc_destroy_state(crtc, crtc->state);
>> - __drm_atomic_helper_crtc_reset(crtc, &cstate->base);
>> + if (cstate)
>> + __drm_atomic_helper_crtc_reset(crtc, &cstate->base);
>> + else
>> + __drm_atomic_helper_crtc_reset(crtc, NULL);
>
> NAK.
>
> The proper fix is to add the if() but to skip the else clause. We should
> not reset the crtc's state if memory allocation failed.
On the other hand... Some of the drivers do exactly this ops.
With the message fixed:
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
--
With best wishes
Dmitry
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