linux-kernel - Re: [PATCH] auxdisplay: fix use after free in lcd2s_i2c

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Date:   Mon, 9 Nov 2020 10:34:01 +0100
From:   Lars Poeschel <poeschel@...onage.de>
To:     Dan Carpenter <dan.carpenter@...cle.com>
Cc:     Miguel Ojeda Sandonis <miguel.ojeda.sandonis@...il.com>,
        linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org
Subject: Re: [PATCH] auxdisplay: fix use after free in lcd2s_i2c_remove()

On Fri, Nov 06, 2020 at 10:24:15PM +0300, Dan Carpenter wrote:
> The kfree() needs to be moved down a line to prevent a use after free.
> 
> Fixes: 8c9108d014c5 ("auxdisplay: add a driver for lcd2s character display")
> Signed-off-by: Dan Carpenter <dan.carpenter@...cle.com>
> ---
>  drivers/auxdisplay/lcd2s.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/auxdisplay/lcd2s.c b/drivers/auxdisplay/lcd2s.c
> index cfa5f86deeef..3eb7f04db6cb 100644
> --- a/drivers/auxdisplay/lcd2s.c
> +++ b/drivers/auxdisplay/lcd2s.c
> @@ -348,8 +348,8 @@ static int lcd2s_i2c_remove(struct i2c_client *i2c)
>  {
>  	struct lcd2s_data *lcd2s = i2c_get_clientdata(i2c);
>  
> -	kfree(lcd2s->charlcd);
>  	charlcd_unregister(lcd2s->charlcd);
> +	kfree(lcd2s->charlcd);
>  	return 0;
>  }

Reviewed-by: Lars Pöschel <poeschel@...onage.de>

Thanks,
Lars