linux-kernel - Re: [PATCH] i2c: dev: Fix memory leak when underlying adapter does not support I2C

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Message-ID: <jc76qean5mqxba4nh5qdocxhl5aa7r4epryyviqkyktbu6grog@u43wzsaki23k>
Date: Thu, 7 Nov 2024 18:14:29 +0100
From: Andi Shyti <andi.shyti@...nel.org>
To: Igor Pylypiv <ipylypiv@...gle.com>
Cc: Wolfram Sang <wsa+renesas@...g-engineering.com>, 
	Jean Delvare <jdelvare@...e.de>, linux-i2c@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] i2c: dev: Fix memory leak when underlying adapter does
 not support I2C

Hi Igor,

that's a good catch, but...

On Thu, Nov 07, 2024 at 01:48:27AM +0000, Igor Pylypiv wrote:
> i2cdev_ioctl_rdwr() receives a buffer which is allocated by the caller.

This needs to be a bit re-written. In the commit log you should
describe what the patch does. You are telling where the buffer is
allocated.

> Fixes: 97ca843f6ad3 ("i2c: dev: Check for I2C_FUNC_I2C before calling i2c_transfer")
> Signed-off-by: Igor Pylypiv <ipylypiv@...gle.com>
> ---
>  drivers/i2c/i2c-dev.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/i2c/i2c-dev.c b/drivers/i2c/i2c-dev.c
> index 61f7c4003d2f..5d15519ef737 100644
> --- a/drivers/i2c/i2c-dev.c
> +++ b/drivers/i2c/i2c-dev.c
> @@ -247,8 +247,10 @@ static noinline int i2cdev_ioctl_rdwr(struct i2c_client *client,
>  	int i, res;
>  
>  	/* Adapter must support I2C transfers */
> -	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
> +	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
> +		kfree(msgs);
>  		return -EOPNOTSUPP;

Please, don't free it here, free it where it has been allocated,
i.e. in compat_i2cdev_ioctl().

Andi

> +	}
>  
>  	data_ptrs = kmalloc_array(nmsgs, sizeof(u8 __user *), GFP_KERNEL);
>  	if (data_ptrs == NULL) {
> -- 
> 2.47.0.277.g8800431eea-goog
>