All of lore.kernel.org
 help / color / mirror / Atom feed
From: Dan Carpenter <error27@gmail.com>
To: Andi Kleen <andi@firstfloor.org>
Cc: Nelson Elhage <nelhage@ksplice.com>,
	Eric Dumazet <eric.dumazet@gmail.com>,
	"David S. Miller" <davem@davemloft.net>,
	Robert Olsson <robert.olsson@its.uu.se>,
	Andy Shevchenko <andy.shevchenko@gmail.com>,
	netdev@vger.kernel.org
Subject: Re: [patch v3] fix stack overflow in pktgen_if_write()
Date: Mon, 1 Nov 2010 05:47:35 +0200	[thread overview]
Message-ID: <20101101034721.GA14069@bicker> (raw)
In-Reply-To: <87lj5hud36.fsf@basil.nowhere.org>

> > @@ -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

  reply	other threads:[~2010-11-01  3:47 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-10-27 19:13 [PATCH] pktgen: Remove a dangerous debug print Nelson Elhage
2010-10-27 19:21 ` David Miller
2010-10-27 19:28   ` Nelson Elhage
2010-10-27 19:30     ` David Miller
2010-10-27 19:41     ` Eric Dumazet
2010-10-27 19:49       ` Nelson Elhage
2010-10-27 20:38 ` Ben Greear
2010-10-27 22:12 ` [patch] fix stack overflow in pktgen_if_write() Dan Carpenter
2010-10-27 22:40   ` Dan Carpenter
2010-10-27 22:43   ` [patch v2] " Dan Carpenter
2010-10-27 23:06     ` Nelson Elhage
2010-10-28  6:05       ` Dan Carpenter
2010-10-28  6:05       ` [patch v3] " Dan Carpenter
2010-10-28 15:22         ` Nelson Elhage
2010-10-28 16:28           ` Dan Carpenter
2010-10-28 16:30             ` Nelson Elhage
2010-10-28 23:11         ` Andi Kleen
2010-11-01  3:47           ` Dan Carpenter [this message]
2010-10-28 15:20 ` [PATCH] pktgen: Limit how much data we copy onto the stack Nelson Elhage
2010-10-28 18:32   ` David Miller

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20101101034721.GA14069@bicker \
    --to=error27@gmail.com \
    --cc=andi@firstfloor.org \
    --cc=andy.shevchenko@gmail.com \
    --cc=davem@davemloft.net \
    --cc=eric.dumazet@gmail.com \
    --cc=nelhage@ksplice.com \
    --cc=netdev@vger.kernel.org \
    --cc=robert.olsson@its.uu.se \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.