linux-kernel - Re: [PATCH] clk: fix a missing-free bug in clk_cpy

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Date:   Wed, 5 Jun 2019 08:38:00 +0200
From:   Jiri Slaby <jslaby@...e.cz>
To:     Gen Zhang <blackgod016574@...il.com>, mturquette@...libre.com,
        sboyd@...nel.org
Cc:     linux-clk@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] clk: fix a missing-free bug in clk_cpy_name()

On 31. 05. 19, 3:14, Gen Zhang wrote:
> In clk_cpy_name(), '*dst_p'('parent->name'and 'parent->fw_name') and 
> 'dst' are allcoted by kstrdup_const(). According to doc: "Strings 
> allocated by kstrdup_const should be freed by kfree_const". So 
> 'parent->name', 'parent->fw_name' and 'dst' should be freed.
> 
> Signed-off-by: Gen Zhang <blackgod016574@...il.com>
> ---
> diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
> index aa51756..85c4d3f 100644
> --- a/drivers/clk/clk.c
> +++ b/drivers/clk/clk.c
> @@ -3435,6 +3435,7 @@ static int clk_cpy_name(const char **dst_p, const char *src, bool must_exist)
>  	if (!dst)
>  		return -ENOMEM;
>  
> +	kfree_const(dst);

So you are now returning a freed pointer in dst_p?

>  	return 0;
>  }
>  
> @@ -3491,6 +3492,8 @@ static int clk_core_populate_parent_map(struct clk_core *core)
>  				kfree_const(parents[i].name);
>  				kfree_const(parents[i].fw_name);
>  			} while (--i >= 0);
> +			kfree_const(parent->name);
> +			kfree_const(parent->fw_name);

Both of them were just freed in the loop above, no?

thanks,
-- 
js
suse labs