linux-kernel - Re: [PATCH] firewire: prevent integer overflow on 32bit systems

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Message-ID: <20210302221911.6c1582e2@kant>
Date:   Tue, 2 Mar 2021 22:19:11 +0100
From:   Stefan Richter <stefanr@...6.in-berlin.de>
To:     Dan Carpenter <dan.carpenter@...cle.com>
Cc:     linux1394-devel@...ts.sourceforge.net,
        linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org
Subject: Re: [PATCH] firewire: prevent integer overflow on 32bit systems

On Mar 02 Dan Carpenter wrote:
> In TCODE_STREAM_DATA mode, on 32bit systems, the "sizeof(*e) +
> request->length" operation can overflow leading to memory corruption.
> 
> Fixes: 18e9b10fcdc0 ("firewire: cdev: add closure to async stream ioctl")
> Signed-off-by: Dan Carpenter <dan.carpenter@...cle.com>
> ---
>  drivers/firewire/core-cdev.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/firewire/core-cdev.c b/drivers/firewire/core-cdev.c
> index fb6c651214f3..314de0384035 100644
> --- a/drivers/firewire/core-cdev.c
> +++ b/drivers/firewire/core-cdev.c
> @@ -587,6 +587,9 @@ static int init_request(struct client *client,
>  	    request->length < 4)
>  		return -EINVAL;
>  
> +	if (request->length > ULONG_MAX - sizeof(*e))
> +		return -EINVAL;
> +
>  	e = kmalloc(sizeof(*e) + request->length, GFP_KERNEL);
>  	if (e == NULL)
>  		return -ENOMEM;

There is already a length check for asynchronous stream requests.
It happens in ioctl_send_stream_packet().
-- 
Stefan Richter
-======--=-= --== ---=-
http://arcgraph.de/sr/