linux-kernel - Re: [PATCH] drm/msm/dpu: Add callback function pointer check before its call

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Date: Wed, 10 Apr 2024 14:45:13 +0300
From: Aleksandr Mishin <amishin@...rgos.ru>
To: Abhinav Kumar <quic_abhinavk@...cinc.com>, Dmitry Baryshkov
	<dmitry.baryshkov@...aro.org>
CC: Rob Clark <robdclark@...il.com>, Sean Paul <sean@...rly.run>, Marijn
 Suijten <marijn.suijten@...ainline.org>, David Airlie <airlied@...il.com>,
	Daniel Vetter <daniel@...ll.ch>, Neil Armstrong <neil.armstrong@...aro.org>,
	Stephen Boyd <swboyd@...omium.org>, <linux-arm-msm@...r.kernel.org>,
	<dri-devel@...ts.freedesktop.org>, <freedreno@...ts.freedesktop.org>,
	<linux-kernel@...r.kernel.org>, <lvc-project@...uxtesting.org>
Subject: Re: [PATCH] drm/msm/dpu: Add callback function pointer check before
 its call



On 08.04.2024 19:51, Abhinav Kumar wrote:
> 
> 
> On 4/8/2024 1:55 AM, Aleksandr Mishin wrote:
>> In dpu_core_irq_callback_handler() callback function pointer is 
>> compared to NULL,
>> but then callback function is unconditionally called by this pointer.
>> Fix this bug by adding conditional return.
>>
>> Found by Linux Verification Center (linuxtesting.org) with SVACE.
>>
> 
> Yes , as dmitry wrote, this should be Reported-by.
> 

It is an established practice for our project, you can find 700+ applied
patches with similar line:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/log/?qt=grep&q=linuxtesting.org

> But rest LGTM.
> 
>> Fixes: c929ac60b3ed ("drm/msm/dpu: allow just single IRQ callback")
>> Signed-off-by: Aleksandr Mishin <amishin@...rgos.ru>
>> ---
>>   drivers/gpu/drm/msm/disp/dpu1/dpu_hw_interrupts.c | 4 +++-
>>   1 file changed, 3 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_interrupts.c 
>> b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_interrupts.c
>> index 946dd0135dff..03a16fbd4c99 100644
>> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_interrupts.c
>> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_interrupts.c
>> @@ -223,9 +223,11 @@ static void dpu_core_irq_callback_handler(struct 
>> dpu_kms *dpu_kms, unsigned int
>>       VERB("IRQ=[%d, %d]\n", DPU_IRQ_REG(irq_idx), DPU_IRQ_BIT(irq_idx));
>> -    if (!irq_entry->cb)
>> +    if (!irq_entry->cb) {
>>           DRM_ERROR("no registered cb, IRQ=[%d, %d]\n",
>>                 DPU_IRQ_REG(irq_idx), DPU_IRQ_BIT(irq_idx));
>> +        return;
>> +    }
>>       atomic_inc(&irq_entry->count);

-- 
Kind regards
Aleksandr