linux-kernel - Re: [PATCH] spi: oc-tiny: fix negative loop bound error on for loop

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Date:   Sun, 31 Mar 2019 14:53:02 +0530
From:   Mukesh Ojha <mojha@...eaurora.org>
To:     Colin King <colin.king@...onical.com>,
        Mark Brown <broonie@...nel.org>, linux-spi@...r.kernel.org
Cc:     kernel-janitors@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] spi: oc-tiny: fix negative loop bound error on for loop


On 3/31/2019 2:53 AM, Colin King wrote:
> From: Colin Ian King <colin.king@...onical.com>
>
> Currently the for-loop using an unsigned int for the loop counter
> which is problematic when comparing it to the signed int
> gt->gpio_cs_count.  This is an issue because if the signed int is
> negative (for example, the call to of_gpio_count failed) then
> the negative loop bound is implicitly cast to an unsigned int on
> the comparison to loop counter i and will yield a very large value,
> eventually causing an array bounds overflow on hw->gpio_cs.
>
> Fix this by simply making the loop counter i a signed int;
>
> Fixes: ca632f556697 ("spi: reorganize drivers")
> Signed-off-by: Colin Ian King <colin.king@...onical.com>
> ---
>   drivers/spi/spi-oc-tiny.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/spi/spi-oc-tiny.c b/drivers/spi/spi-oc-tiny.c
> index 085f580be7ec..81f74b938dc9 100644
> --- a/drivers/spi/spi-oc-tiny.c
> +++ b/drivers/spi/spi-oc-tiny.c
> @@ -206,7 +206,7 @@ static int tiny_spi_of_probe(struct platform_device *pdev)
>   {
>   	struct tiny_spi *hw = platform_get_drvdata(pdev);
>   	struct device_node *np = pdev->dev.of_node;
> -	unsigned int i;
> +	int i;


same here as well you are putting wrapper over a original issue by not 
checking the returned value.
Please fix that in both patches.



Thanks.
Mukesh

>   	u32 val;
>   
>   	if (!np)