linux-kernel - Re: drivers/gpu/drm/msm/adreno/a2xx_gpu.c:503 a2xx_gpu_init() warn: variable dereferenced before check 'pdev' (see line 500)

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Message-ID: <ca0bebc1-849e-47a9-8a75-9fe7ba0064f2@oss.qualcomm.com>
Date: Thu, 25 Dec 2025 00:07:31 +0530
From: Akhil P Oommen <akhilpo@....qualcomm.com>
To: Dan Carpenter <dan.carpenter@...aro.org>, oe-kbuild@...ts.linux.dev
Cc: lkp@...el.com, oe-kbuild-all@...ts.linux.dev, linux-kernel@...r.kernel.org,
        Rob Clark <robin.clark@....qualcomm.com>
Subject: Re: drivers/gpu/drm/msm/adreno/a2xx_gpu.c:503 a2xx_gpu_init() warn:
 variable dereferenced before check 'pdev' (see line 500)

On 12/9/2025 1:40 PM, Dan Carpenter wrote:
> tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
> head:   c2f2b01b74be8b40a2173372bcd770723f87e7b2
> commit: 491fadb2b818e1d900229a1f8243de6458381306 drm/msm/adreno: Move adreno_gpu_func to catalogue
> config: arm64-randconfig-r072-20251207 (https://download.01.org/0day-ci/archive/20251208/202512082235.2rH8XoPX-lkp@intel.com/config)
> compiler: clang version 22.0.0git (https://github.com/llvm/llvm-project a805147ac1ba123916de182babb0831fbb148756)
> 
> If you fix the issue in a separate patch/commit (i.e. not just a new version of
> the same patch/commit), kindly add following tags
> | Reported-by: kernel test robot <lkp@...el.com>
> | Reported-by: Dan Carpenter <dan.carpenter@...aro.org>
> | Closes: https://lore.kernel.org/r/202512082235.2rH8XoPX-lkp@intel.com/
> 
> smatch warnings:
> drivers/gpu/drm/msm/adreno/a2xx_gpu.c:503 a2xx_gpu_init() warn: variable dereferenced before check 'pdev' (see line 500)
> drivers/gpu/drm/msm/adreno/a3xx_gpu.c:530 a3xx_gpu_init() warn: variable dereferenced before check 'pdev' (see line 525)
> drivers/gpu/drm/msm/adreno/a4xx_gpu.c:642 a4xx_gpu_init() warn: variable dereferenced before check 'pdev' (see line 637)
> 
> vim +/pdev +503 drivers/gpu/drm/msm/adreno/a2xx_gpu.c
> 
> 491fadb2b818e1 Akhil P Oommen 2025-11-18  493  static struct msm_gpu *a2xx_gpu_init(struct drm_device *dev)
> 21af872cd8c695 Jonathan Marek 2018-11-21  494  {
> 21af872cd8c695 Jonathan Marek 2018-11-21  495  	struct a2xx_gpu *a2xx_gpu = NULL;
> 21af872cd8c695 Jonathan Marek 2018-11-21  496  	struct adreno_gpu *adreno_gpu;
> 21af872cd8c695 Jonathan Marek 2018-11-21  497  	struct msm_gpu *gpu;
> 21af872cd8c695 Jonathan Marek 2018-11-21  498  	struct msm_drm_private *priv = dev->dev_private;
> 21af872cd8c695 Jonathan Marek 2018-11-21  499  	struct platform_device *pdev = priv->gpu_pdev;
> 491fadb2b818e1 Akhil P Oommen 2025-11-18 @500  	struct adreno_platform_config *config = pdev->dev.platform_data;
>                                                                                         ^^^^^^^^^
> Patch adds a dereference.
> 
> 21af872cd8c695 Jonathan Marek 2018-11-21  501  	int ret;
> 21af872cd8c695 Jonathan Marek 2018-11-21  502  
> 21af872cd8c695 Jonathan Marek 2018-11-21 @503  	if (!pdev) {
> 
> but the old code checked for NULL.  Probably this NULL check can be
> removed?

Yes, we can remove this unnecessary check. I will send a patch. Thanks.

-Akhil.

> 
> 21af872cd8c695 Jonathan Marek 2018-11-21  504  		dev_err(dev->dev, "no a2xx device\n");
> 21af872cd8c695 Jonathan Marek 2018-11-21  505  		ret = -ENXIO;
> 21af872cd8c695 Jonathan Marek 2018-11-21  506  		goto fail;
> 21af872cd8c695 Jonathan Marek 2018-11-21  507  	}
> 21af872cd8c695 Jonathan Marek 2018-11-21  508  
> 21af872cd8c695 Jonathan Marek 2018-11-21  509  	a2xx_gpu = kzalloc(sizeof(*a2xx_gpu), GFP_KERNEL);
> 21af872cd8c695 Jonathan Marek 2018-11-21  510  	if (!a2xx_gpu) {
> 21af872cd8c695 Jonathan Marek 2018-11-21  511  		ret = -ENOMEM;
> 21af872cd8c695 Jonathan Marek 2018-11-21  512  		goto fail;
> 21af872cd8c695 Jonathan Marek 2018-11-21  513  	}
> 21af872cd8c695 Jonathan Marek 2018-11-21  514  
> 21af872cd8c695 Jonathan Marek 2018-11-21  515  	adreno_gpu = &a2xx_gpu->base;
> 21af872cd8c695 Jonathan Marek 2018-11-21  516  	gpu = &adreno_gpu->base;
> 21af872cd8c695 Jonathan Marek 2018-11-21  517  
> 21af872cd8c695 Jonathan Marek 2018-11-21  518  	gpu->perfcntrs = perfcntrs;
> 21af872cd8c695 Jonathan Marek 2018-11-21  519  	gpu->num_perfcntrs = ARRAY_SIZE(perfcntrs);
> 21af872cd8c695 Jonathan Marek 2018-11-21  520  
> 491fadb2b818e1 Akhil P Oommen 2025-11-18  521  	ret = adreno_gpu_init(dev, pdev, adreno_gpu, config->info->funcs, 1);
> db07ce5da8b26b Fabio Estevam  2023-06-20  522  	if (ret)
> db07ce5da8b26b Fabio Estevam  2023-06-20  523  		goto fail;
> db07ce5da8b26b Fabio Estevam  2023-06-20  524  
> 21af872cd8c695 Jonathan Marek 2018-11-21  525  	if (adreno_is_a20x(adreno_gpu))
> 21af872cd8c695 Jonathan Marek 2018-11-21  526  		adreno_gpu->registers = a200_registers;
> 21af872cd8c695 Jonathan Marek 2018-11-21  527  	else if (adreno_is_a225(adreno_gpu))
> 21af872cd8c695 Jonathan Marek 2018-11-21  528  		adreno_gpu->registers = a225_registers;
> 21af872cd8c695 Jonathan Marek 2018-11-21  529  	else
> 21af872cd8c695 Jonathan Marek 2018-11-21  530  		adreno_gpu->registers = a220_registers;
> 21af872cd8c695 Jonathan Marek 2018-11-21  531  
> 21af872cd8c695 Jonathan Marek 2018-11-21  532  	return gpu;
> 21af872cd8c695 Jonathan Marek 2018-11-21  533  
> 21af872cd8c695 Jonathan Marek 2018-11-21  534  fail:
> 21af872cd8c695 Jonathan Marek 2018-11-21  535  	if (a2xx_gpu)
> 21af872cd8c695 Jonathan Marek 2018-11-21  536  		a2xx_destroy(&a2xx_gpu->base.base);
> 21af872cd8c695 Jonathan Marek 2018-11-21  537  
> 21af872cd8c695 Jonathan Marek 2018-11-21  538  	return ERR_PTR(ret);
> 21af872cd8c695 Jonathan Marek 2018-11-21  539  }
>