linux-kernel - Re: [PATCH v2] ipmi: Fix NULL pointer dereference in ssif

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Message-ID: <6efd45da-8b35-b1c8-bd0e-148c578c99f5@acm.org>
Date:   Fri, 31 Aug 2018 14:15:32 -0500
From:   Corey Minyard <minyard@....org>
To:     "Gustavo A. R. Silva" <gustavo@...eddedor.com>,
        Arnd Bergmann <arnd@...db.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     openipmi-developer@...ts.sourceforge.net,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] ipmi: Fix NULL pointer dereference in ssif_probe

On 08/31/2018 10:00 AM, Gustavo A. R. Silva wrote:
> There is a potential execution path in which function ssif_info_find()
> returns NULL, hence there is a NULL pointer dereference when accessing
> pointer *addr_info*
>
> Fix this by null checking *addr_info* before dereferencing it.

Thanks for catching this quickly, before it went out.  It's merged into 
my next tree.

-corey

> Addresses-Coverity-ID: 1473145 ("Explicit null dereferenced")
> Fixes: e333054a91d1 ("ipmi: Fix I2C client removal in the SSIF driver")
> Signed-off-by: Gustavo A. R. Silva <gustavo@...eddedor.com>
> ---
> Changes in v2:
>   - Fix typo in commit log.
>
>   drivers/char/ipmi/ipmi_ssif.c | 4 +++-
>   1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/char/ipmi/ipmi_ssif.c b/drivers/char/ipmi/ipmi_ssif.c
> index 2ff3679..764d305 100644
> --- a/drivers/char/ipmi/ipmi_ssif.c
> +++ b/drivers/char/ipmi/ipmi_ssif.c
> @@ -1641,7 +1641,9 @@ static int ssif_probe(struct i2c_client *client, const struct i2c_device_id *id)
>   
>    out:
>   	if (rv) {
> -		addr_info->client = NULL;
> +		if (addr_info)
> +			addr_info->client = NULL;
> +
>   		dev_err(&client->dev, "Unable to start IPMI SSIF: %d\n", rv);
>   		kfree(ssif_info);
>   	}