linux-kernel - Re: [PATCH v2] misc: sram: fix check of devm

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Message-ID: <57143472.8080100@mleia.com>
Date:	Mon, 18 Apr 2016 04:12:18 +0300
From:	Vladimir Zapolskiy <vz@...ia.com>
To:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:	Arnd Bergmann <arnd@...db.de>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] misc: sram: fix check of devm_ioremap*() return value

Hi Greg,

On 23.03.2016 04:52, Vladimir Zapolskiy wrote:
> Both devm_ioremap() and devm_ioremap_wc() functions return either
> a pointer to valid iomem region or NULL, check for IS_ERR() is improper
> and may result in oops on error path. Now on error -ENOMEM is returned.
> 
> Fixes: 0ab163ad1ea0 ("misc: sram: switch to ioremap_wc from ioremap")
> Signed-off-by: Vladimir Zapolskiy <vz@...ia.com>
> ---
> I add Fixes: tag for reference, but unfortunately the change can not
> be cleanly applied to kernel versions liable to the problem.
> 
> Changes from v1 to v2:
> - had to rebase on top of eb43e023130b ("misc: sram: add optional ioremap without write combining")
> - slightly reworded the commit message and subject
> 
> v1 of the change: https://lkml.org/lkml/2016/3/6/202
> 

this is a trivial fix of a potential NULL pointer dereference,
do you have any review comments?

>  drivers/misc/sram.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/misc/sram.c b/drivers/misc/sram.c
> index 69cdabe..f84b53d 100644
> --- a/drivers/misc/sram.c
> +++ b/drivers/misc/sram.c
> @@ -364,8 +364,8 @@ static int sram_probe(struct platform_device *pdev)
>  		sram->virt_base = devm_ioremap(sram->dev, res->start, size);
>  	else
>  		sram->virt_base = devm_ioremap_wc(sram->dev, res->start, size);
> -	if (IS_ERR(sram->virt_base))
> -		return PTR_ERR(sram->virt_base);
> +	if (!sram->virt_base)
> +		return -ENOMEM;
>  
>  	sram->pool = devm_gen_pool_create(sram->dev, ilog2(SRAM_GRANULARITY),
>  					  NUMA_NO_NODE, NULL);
> 

--
With best wishes,
Vladimir