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

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Date:   Wed, 3 Mar 2021 08:22:40 +0300
From:   Dan Carpenter <dan.carpenter@...cle.com>
To:     Stefan Richter <stefanr@...6.in-berlin.de>
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 Tue, Mar 02, 2021 at 10:19:11PM +0100, Stefan Richter wrote:
> 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().

Oh, yeah.  You're right.  I should have looked more carefully.  Sorry.

regards,
dan carpenter