linux-kernel - Re: [PATCH] mmc: pxamci: Fix passing NULL to PTR_ERR() in pxamci

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Message-ID: <a5a86f30-4e52-4694-a6e4-3b71d46c793b@kernel.org>
Date: Tue, 7 Oct 2025 11:43:07 -0600
From: Khalid Aziz <khalid@...nel.org>
To: Rakuram Eswaran <rakuram.e96@...il.com>, ulf.hansson@...aro.org
Cc: zhoubinbin@...ngson.cn, u.kleine-koenig@...libre.com,
 chenhuacai@...nel.org, david.hunter.linux@...il.com,
 skhan@...uxfoundation.org, linux-mmc@...r.kernel.org,
 linux-kernel@...r.kernel.org, linux-kernel-mentees@...ts.linux.dev,
 kernel test robot <lkp@...el.com>, Dan Carpenter <dan.carpenter@...aro.org>
Subject: Re: [PATCH] mmc: pxamci: Fix passing NULL to PTR_ERR() in
 pxamci_probe()

On 10/7/25 10:17 AM, Rakuram Eswaran wrote:
> Smatch reported:
> drivers/mmc/host/pxamci.c:709 pxamci_probe() warn: passing zero to 'PTR_ERR'
> 
> Case 1:
> When dma_request_chan() fails, host->dma_chan_rx is an ERR_PTR(),
> but it is reset to NULL before using PTR_ERR(), resulting in PTR_ERR(0).
> This mistakenly returns 0 instead of the real error code.
> 
> Case 2:
> When devm_clk_get() fails, host->clk is an ERR_PTR() resulting in the similar
> issue like case 1.
> 
> Store the error code before nullifying the pointers in both the cases.
> 
> Reported-by: kernel test robot <lkp@...el.com>
> Reported-by: Dan Carpenter <dan.carpenter@...aro.org>
> Closes: https://lore.kernel.org/r/202510041841.pRlunIfl-lkp@intel.com/
> Fixes: 58c40f3faf742c ("mmc: pxamci: Use devm_mmc_alloc_host() helper")
> Signed-off-by: Rakuram Eswaran <rakuram.e96@...il.com>
> ---
> 
> Build and Analysis:
> This patch was compiled against the configuration file reported by
> 0day CI in the above link (config: s390-randconfig-r071-20251004) using
> `s390x-linux-gnu-gcc (Ubuntu 14.2.0-19ubuntu2) 14.2.0`.
> 
> Static analysis was performed with Smatch to ensure the reported warning
> no longer reproduces after applying this fix.
> 
> Command used for verification:
>    ARCH=s390 CROSS_COMPILE=s390x-linux-gnu- \
>    ~/project/smatch/smatch_scripts/kchecker ./drivers/mmc/host/pxamci.c
> 
>   drivers/mmc/host/pxamci.c | 6 ++++--
>   1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/mmc/host/pxamci.c b/drivers/mmc/host/pxamci.c
> index 26d03352af63..4fab693d3b32 100644
> --- a/drivers/mmc/host/pxamci.c
> +++ b/drivers/mmc/host/pxamci.c
> @@ -653,8 +653,9 @@ static int pxamci_probe(struct platform_device *pdev)
>   
>   	host->clk = devm_clk_get(dev, NULL);
>   	if (IS_ERR(host->clk)) {
> +		ret = PTR_ERR(host->clk);
>   		host->clk = NULL;
> -		return PTR_ERR(host->clk);
> +		return ret;
>   	}
>   
>   	host->clkrate = clk_get_rate(host->clk);
> @@ -705,8 +706,9 @@ static int pxamci_probe(struct platform_device *pdev)
>   
>   	host->dma_chan_rx = dma_request_chan(dev, "rx");
>   	if (IS_ERR(host->dma_chan_rx)) {
> +		ret = PTR_ERR(host->dma_chan_rx);
>   		host->dma_chan_rx = NULL;
> -		return dev_err_probe(dev, PTR_ERR(host->dma_chan_rx),
> +		return dev_err_probe(dev, ret,
>   				     "unable to request rx dma channel\n");
>   	}
>   

This looks good to me.

Reviewed-by: Khalid Aziz <khalid@...nel.org>

--
Khalid