linux-kernel - Re: [PATCH] clk: zynq: Prevent null pointer dereference caused by kmalloc failure

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Message-ID: <86e1c66c-8fd4-402e-a827-cc4347d468c1@amd.com>
Date: Mon, 19 Feb 2024 14:35:01 +0100
From: Michal Simek <michal.simek@....com>
To: Duoming Zhou <duoming@....edu.cn>, linux-kernel@...r.kernel.org
Cc: mturquette@...libre.com, sboyd@...nel.org, linux-clk@...r.kernel.org,
 linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH] clk: zynq: Prevent null pointer dereference caused by
 kmalloc failure



On 2/14/24 08:33, Duoming Zhou wrote:
> The kmalloc in zynq_clk_setup will return null if the
> physical memory has run out. As a result, if we use
> snprintf to write data to the null address, the null
> pointer dereference bug will happen.
> 
> The required memory is only 11 bytes, so this patch
> adds a "__GFP_NOFAIL" flag in kmalloc in order that
> the kmalloc will never return with failure.
> 
> Fixes: 0ee52b157b8e ("clk: zynq: Add clock controller driver")
> Signed-off-by: Duoming Zhou <duoming@....edu.cn>
> ---
>   drivers/clk/zynq/clkc.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/clk/zynq/clkc.c b/drivers/clk/zynq/clkc.c
> index 7bdeaff2bfd..7621c2f0046 100644
> --- a/drivers/clk/zynq/clkc.c
> +++ b/drivers/clk/zynq/clkc.c
> @@ -427,7 +427,7 @@ static void __init zynq_clk_setup(struct device_node *np)
>   			SLCR_GEM1_CLK_CTRL, 0, 0, &gem1clk_lock);
>   
>   	tmp = strlen("mio_clk_00x");
> -	clk_name = kmalloc(tmp, GFP_KERNEL);
> +	clk_name = kmalloc(tmp, GFP_KERNEL | __GFP_NOFAIL);
>   	for (i = 0; i < NUM_MIO_PINS; i++) {
>   		int idx;
>   

Reviewed-by: Michal Simek <michal.simek@....com>

Thanks,
Michal