netdev - Re: [patch v3] fix stack overflow in pktgen_if

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <20101101034721.GA14069@bicker>
Date:	Mon, 1 Nov 2010 05:47:35 +0200
From:	Dan Carpenter <error27@...il.com>
To:	Andi Kleen <andi@...stfloor.org>
Cc:	Nelson Elhage <nelhage@...lice.com>,
	Eric Dumazet <eric.dumazet@...il.com>,
	"David S. Miller" <davem@...emloft.net>,
	Robert Olsson <robert.olsson@....uu.se>,
	Andy Shevchenko <andy.shevchenko@...il.com>,
	netdev@...r.kernel.org
Subject: Re: [patch v3] fix stack overflow in pktgen_if_write()

> > @@ -887,12 +887,17 @@ static ssize_t pktgen_if_write(struct file *file,
> >  	i += len;
> >  
> >  	if (debug) {
> > -		char tb[count + 1];
> > +		char *tb;
> > +
> > +		tb = kmalloc(count + 1, GFP_KERNEL);
> 
> 
> This is still trivially exploitable (for root) -- think what happens
> when count is near ULONG_MAX
> 

In vfs_write() we call rw_verify_area() which caps count at INT_MAX or
LONG_MAX.

        if (unlikely((ssize_t) count < 0))
                return retval;

So I get lucky this time...  ;)

regards,
dan carpenter
--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html