Date: Sat, 25 Jan 2003 20:00:21 +0100 (CET) From: "=?iso-8859-1?q?Pedro=20F.=20Giffuni?=" <giffunip@yahoo.com> To: freebsd-hackers@FreeBSD.org Subject: idea from NetBSD: signal trampoline on libc ? Message-ID: <20030125190021.80728.qmail@web13402.mail.yahoo.com>
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Hi; I was reading an interview about IRIX binary compatibility on NetBSD, and it looks like they learned a few tricks. This article gets into their native implementation of signals: http://www.onlamp.com/pub/a/bsd/2002/10/10/irix.html At the end of the article Emmanuel Dreyfus mentions: "One other interesting thing to note is that since that code was written, Jason Thorpe implemented signal trampolines provided by libc for NetBSD native processes, thus adopting the same scheme IRIX used. The libc provided signal trampoline was adopted in NetBSD because it removes the need to execute code on the stack. Memory pages mapped on the stack can therefore be made non executable (the Memory Management Unit of all modern CPU are able to enforce such rules), and we are able to fix a whole class of security problems. With a non executable stack, it is not possible anymore to exploit a buffer overflow on a local variable by executing some user-supplied code stored on the stack." A drastic change that maybe we should consider? cheers, Pedro. ______________________________________________________________________ Yahoo! Cellulari: loghi, suonerie, picture message per il tuo telefonino http://it.yahoo.com/mail_it/foot/?http://it.mobile.yahoo.com/index2002.html To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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