linux-kernel - Re: [PATCH] ipmi: kcs_bmc: Fix a memory leak in the error handling path of 'kcs_bmc_serio_add

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Message-ID: <20210908062719.GO1957@kadam>
Date:   Wed, 8 Sep 2021 09:27:19 +0300
From:   Dan Carpenter <dan.carpenter@...cle.com>
To:     Christophe JAILLET <christophe.jaillet@...adoo.fr>
Cc:     minyard@....org, zweiss@...inix.com, andrew@...id.au,
        openipmi-developer@...ts.sourceforge.net,
        linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org
Subject: Re: [PATCH] ipmi: kcs_bmc: Fix a memory leak in the error handling
 path of 'kcs_bmc_serio_add_device()'

On Tue, Sep 07, 2021 at 11:06:32PM +0200, Christophe JAILLET wrote:
> In the unlikely event where 'devm_kzalloc()' fails and 'kzalloc()'
> succeeds, 'port' would be leaking.
> 
> Test each allocation separately to avoid the leak.
> 
> Fixes: 3a3d2f6a4c64 ("ipmi: kcs_bmc: Add serio adaptor")
> Signed-off-by: Christophe JAILLET <christophe.jaillet@...adoo.fr>
> ---
>  drivers/char/ipmi/kcs_bmc_serio.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/char/ipmi/kcs_bmc_serio.c b/drivers/char/ipmi/kcs_bmc_serio.c
> index 7948cabde50b..7e2067628a6c 100644
> --- a/drivers/char/ipmi/kcs_bmc_serio.c
> +++ b/drivers/char/ipmi/kcs_bmc_serio.c
> @@ -73,10 +73,12 @@ static int kcs_bmc_serio_add_device(struct kcs_bmc_device *kcs_bmc)
>  	struct serio *port;
>  
>  	priv = devm_kzalloc(kcs_bmc->dev, sizeof(*priv), GFP_KERNEL);
> +	if (!priv)
> +		return -ENOMEM;
>  
>  	/* Use kzalloc() as the allocation is cleaned up with kfree() via serio_unregister_port() */

The serio_unregister_port() calls serio_destroy_port() which calls
put_device(&serio->dev).  But I wasn't able to track it further than
that to the actual kfree().

Is there a trick to finding ->release() functions?

regards,
dan carpenter