From: Ingo Molnar <mingo@redhat.com>
To: "Calin A. Culianu" <calin@ajvar.org>
Cc: Carl-Daniel Hailfinger <c-d.hailfinger.kernel.2003@gmx.net>,
<linux-kernel@vger.kernel.org>
Subject: Re: [Announcement] "Exec Shield", new Linux security feature
Date: Sun, 4 May 2003 04:52:49 -0400 (EDT) [thread overview]
Message-ID: <Pine.LNX.4.44.0305040448250.24497-100000@devserv.devel.redhat.com> (raw)
In-Reply-To: <Pine.LNX.4.44.0305040404300.12757-100000@devserv.devel.redhat.com>
On Sun, 4 May 2003, Ingo Molnar wrote:
> > IIRC, x86 ints have the high-order byte _last_ (ie the fourth byte).
> > What's to stop someone from, say, smashing a buffer (and consequently
> > return-address) on the stack using something like {0x01, 0x01, 0x01,
> > 0x00} which is really address '65793' in base-10. The above is a valid
> > ASCII string (3 1's followed by a NUL) which could conceivably end up on
> > the stack as the result of an errant strcpy() or gets() or whatever...
>
> you are right, it is possible to use the enclosing \0 to generate an
> address into the first 16MB, but how do you get any arguments passed to
> that function?
ie. if the binary anywhere has code that does:
system("/bin/sh")
then this address can be jumped to and an exploit becomes possible. Also,
in the case of non-ASCII overflows the attacker has a much higher degree
of freedom to create a proper stackframe.
wrt. address-space randomization, "prelink -R" already provides quite good
randomization of the shared library addresses, which should give some
statistical protection against remote attacks, i dont think we'll need
kernel support for that.
Ingo
next prev parent reply other threads:[~2003-05-04 8:40 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-05-02 16:37 [Announcement] "Exec Shield", new Linux security feature Ingo Molnar
2003-05-02 17:05 ` Matthias Andree
2003-05-02 17:12 ` Marc-Christian Petersen
2003-05-02 17:12 ` Davide Libenzi
2003-05-02 17:18 ` Arjan van de Ven
2003-05-02 17:32 ` Ingo Molnar
2003-05-02 18:29 ` John Bradford
2003-05-02 18:32 ` H. Peter Anvin
2003-05-02 19:09 ` David Mosberger
2003-05-02 18:51 ` Davide Libenzi
[not found] ` <20030502172011$0947@gated-at.bofh.it>
2003-05-02 18:17 ` Florian Weimer
2003-05-02 18:29 ` Davide Libenzi
2003-05-02 18:32 ` Florian Weimer
2003-05-02 18:50 ` Davide Libenzi
2003-05-02 21:48 ` Carl-Daniel Hailfinger
2003-05-03 6:52 ` Ingo Molnar
2003-05-03 9:56 ` Carl-Daniel Hailfinger
2003-05-03 12:48 ` Arjan van de Ven
2003-05-04 6:52 ` Calin A. Culianu
2003-05-04 8:10 ` Ingo Molnar
2003-05-04 8:52 ` Ingo Molnar [this message]
2003-05-04 15:40 ` Calin A. Culianu
2003-05-04 15:48 ` Sean Neakums
2003-05-04 15:23 ` Calin A. Culianu
2003-05-04 20:07 ` H. Peter Anvin
2003-05-04 20:57 ` Kasper Dupont
2003-05-05 16:20 ` [patch] exec-shield-2.4.21-rc1-C5 Ingo Molnar
[not found] <Pine.LNX.4.44.0305021325130.6565-100000@devserv.devel.redhat.com.suse.lists.linux.kernel>
[not found] ` <200305021829.h42ITclA000178@81-2-122-30.bradfords.org.uk.suse.lists.linux.kernel>
[not found] ` <b8udjm$cgq$1@cesium.transmeta.com.suse.lists.linux.kernel>
2003-05-02 20:51 ` [Announcement] "Exec Shield", new Linux security feature Andi Kleen
2003-05-02 20:56 ` H. Peter Anvin
2003-05-02 21:07 ` Andi Kleen
2003-05-02 21:09 ` H. Peter Anvin
2003-05-02 21:25 ` Andi Kleen
2003-05-02 22:46 Chuck Ebbert
2003-05-03 13:19 linux
2003-05-03 23:00 ` Valdis.Kletnieks
2003-05-04 7:03 ` Calin A. Culianu
2003-05-04 8:49 ` Arjan van de Ven
2003-05-05 13:35 ` Jesse Pollard
2003-05-04 15:24 ` linux
2003-05-04 11:19 Yoav Weiss
2003-05-04 13:51 ` Ingo Molnar
2003-05-04 14:25 Chuck Ebbert
2003-05-04 22:22 ` Richard Henderson
2003-05-05 0:41 ` H. Peter Anvin
[not found] <Pine.LNX.4.44.0305040404300.12757-100000@devserv.devel.redhat.com.suse.lists.linux.kernel>
[not found] ` <Pine.LNX.4.44.0305040448250.24497-100000@devserv.devel.redhat.com.suse.lists.linux.kernel>
2003-05-04 15:48 ` Andi Kleen
2003-05-04 16:20 Yoav Weiss
2003-05-04 23:55 Chuck Ebbert
2003-05-05 3:14 ` H. Peter Anvin
2003-05-05 7:14 Ingo Molnar
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