Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753749Ab0H0Wfl (ORCPT ); Fri, 27 Aug 2010 18:35:41 -0400 Received: from mail-iw0-f174.google.com ([209.85.214.174]:50735 "EHLO mail-iw0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753615Ab0H0Wfk convert rfc822-to-8bit (ORCPT ); Fri, 27 Aug 2010 18:35:40 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc:content-type:content-transfer-encoding; b=tehxNN4m5ezmnNl+mMccNHqBrYTIm1X6ayYVwklH+fd0rvoHWGzJw2plH2MUq6EIzg zRw56pibI9apXauzfIkXGUnZktEj+3Dtx7ZaT4fp+5zYbVipjQun+POUQn+mUorSoYob NNgWyDLNLvVeltX9m8Jtyu9XuhmfIHNAuqUas= MIME-Version: 1.0 In-Reply-To: <20100827212254.GB32275@bougret.hpl.hp.com> References: <20100827210240.GC4703@outflux.net> <20100827212254.GB32275@bougret.hpl.hp.com> From: "Luis R. Rodriguez" Date: Fri, 27 Aug 2010 15:35:19 -0700 Message-ID: Subject: Re: [PATCH] wireless: fix 64K kernel heap content leak via ioctl To: jt@hpl.hp.com Cc: Kees Cook , linux-kernel@vger.kernel.org, "John W. Linville" , "David S. Miller" , Eric Dumazet , Johannes Berg , Joe Perches , Tejun Heo , linux-wireless@vger.kernel.org, netdev@vger.kernel.org Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2625 Lines: 64 On Fri, Aug 27, 2010 at 2:22 PM, Jean Tourrilhes wrote: > On Fri, Aug 27, 2010 at 02:02:41PM -0700, Kees Cook wrote: >> This problem was originally tracked down by Brad Spengler. >> >> When calling wireless ioctls, if a driver does not correctly >> validate/shrink iwp->length, the resulting copy_to_user can leak up to >> 64K of kernel heap contents. >> >> It seems that this is triggerable[1] in 2.6.32 at least on ath5k, but >> I was not able to track down how. The twisty maze of ioctl handlers >> stumped me. :) > >        You can always ask. > >> Other drivers I checked did not appear to have any problems, >> but the potential remains. I'm not sure if this patch is the right approach; >> it was fixed differently[2] in grsecurity. > >        Did you tried your patch for real ? With large scan request ? >        I ask because at first glance, it looks incorrect, asI believe > it kills large request. But someone would need to test, for sure. > >> [1] http://forums.grsecurity.net/viewtopic.php?f=3&t=2290&start=0 >> [2] http://grsecurity.net/~spender/wireless-infoleak-fix2.patch > >        I believe this patch would make the situation worse. > >        Would you mind validating the following patch ? I've just > verified that it compiles and I believe it does what you are asking in > a much more predictable way. >        Regards, > >        Jean > > diff -u -p wext.j2.c wext.c > --- wext.j2.c 2010-08-27 14:17:26.000000000 -0700 > +++ wext.c 2010-08-27 14:19:33.000000000 -0700 > @@ -800,9 +800,12 @@ static int ioctl_standard_iw_point(struc > goto out; > } > > - if (copy_to_user(iwp->pointer, extra, > - iwp->length * > - descr->token_size)) { > + /* Verify how much we should return. Some driver > + * may abuse iwp->length... */ > + if((iwp->length * descr->token_size) < extra_size) > + extra_size = iwp->length * descr->token_size; > + > + if (copy_to_user(iwp->pointer, extra, extra_size)) { > err = -EFAULT; > goto out; > } Jean, can you submit in a new thread and right before the SOB add in the commit log Cc: stable@kernel.org [2.6.32+] Luis -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/