[PATCH] mfd: core: Fix possible ZERO_SIZE_PTR pointer dereferencing error.

[PATCH] mfd: core: Fix possible ZERO_SIZE_PTR pointer dereferencing error.

[Xiubo Li]

Since we cannot make sure the 'cell->num_resources' will always be none
zero here, and then if either equal to zero, the kzalloc() will return
ZERO_SIZE_PTR, which equals to ((void *)16).

So this patch fix this with just doing the zero check before calling
kzalloc().

Signed-off-by: Xiubo Li <Li.Xiubo@freescale.com>
---
 drivers/mfd/mfd-core.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/mfd/mfd-core.c b/drivers/mfd/mfd-core.c
index 892d343..54c7e35 100644
--- a/drivers/mfd/mfd-core.c
+++ b/drivers/mfd/mfd-core.c
@@ -89,6 +89,9 @@ static int mfd_add_device(struct device *parent, int id,
 	int ret = -ENOMEM;
 	int r;
 
+	if (!cell->num_resources)
+		return -EINVAL;
+
 	pdev = platform_device_alloc(cell->name, id + cell->id);
 	if (!pdev)
 		goto fail_alloc;
-- 
2.1.0.27.g96db324

Re: [PATCH] mfd: core: Fix possible ZERO_SIZE_PTR pointer dereferencing error.

[Lee Jones]

On Thu, 18 Sep 2014, Xiubo Li wrote:

> Since we cannot make sure the 'cell->num_resources' will always be none
> zero here, and then if either equal to zero, the kzalloc() will return
> ZERO_SIZE_PTR, which equals to ((void *)16).
> 
> So this patch fix this with just doing the zero check before calling
> kzalloc().
> 
> Signed-off-by: Xiubo Li <Li.Xiubo@freescale.com>
> ---
>  drivers/mfd/mfd-core.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/mfd/mfd-core.c b/drivers/mfd/mfd-core.c
> index 892d343..54c7e35 100644
> --- a/drivers/mfd/mfd-core.c
> +++ b/drivers/mfd/mfd-core.c
> @@ -89,6 +89,9 @@ static int mfd_add_device(struct device *parent, int id,
>  	int ret = -ENOMEM;
>  	int r;
>  
> +	if (!cell->num_resources)
> +		return -EINVAL;

Resources are not compulsory.

>  	pdev = platform_device_alloc(cell->name, id + cell->id);
>  	if (!pdev)
>  		goto fail_alloc;

-- 
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
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