linux-kernel - Re: [PATCH] power: supply: fix null pointer dereferencing in power_supply_get_battery

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Message-ID: <2b6381f9-dc23-05c9-0d24-3c86ccd264bc@linux.alibaba.com>
Date:   Mon, 5 Dec 2022 15:12:17 +0800
From:   Baolin Wang <baolin.wang@...ux.alibaba.com>
To:     ruanjinjie <ruanjinjie@...wei.com>, sre@...nel.org,
        linus.walleij@...aro.org, linux-pm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] power: supply: fix null pointer dereferencing in
 power_supply_get_battery_info

Hi,

On 12/4/2022 10:38 AM, ruanjinjie wrote:
> when kmalloc() fail to allocate memory in kasprintf(), propname
> will be NULL, strcmp() called by of_get_property() will cause
> null pointer dereference.
> 
> So directly return ENOMEM, if kasprintf() return NULL pointer.
> 
> Fixes: 3afb50d7125b ("power: supply: core: Add some helpers to use the battery OCV capacity table")
> Signed-off-by: ruanjinjie <ruanjinjie@...wei.com>
> ---
>   drivers/power/supply/power_supply_core.c | 2 ++
>   1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/power/supply/power_supply_core.c b/drivers/power/supply/power_supply_core.c
> index 4b5fb172fa99..2fd6ab7a4471 100644
> --- a/drivers/power/supply/power_supply_core.c
> +++ b/drivers/power/supply/power_supply_core.c
> @@ -750,6 +750,8 @@ int power_supply_get_battery_info(struct power_supply *psy,
>   		int i, tab_len, size;
>   
>   		propname = kasprintf(GFP_KERNEL, "ocv-capacity-table-%d", index);
> +		if (!propname)
> +			return -ENOMEM;

Please read the code carefully, you can not just return error number 
without releasing resource.

>   		list = of_get_property(battery_np, propname, &size);
>   		if (!list || !size) {
>   			dev_err(&psy->dev, "failed to get %s\n", propname);