Dailydave mailing list archives
Re: gcc 4.1 security features
From: Gadi Evron <ge () linuxbox org>
Date: Thu, 16 Feb 2006 20:44:54 +0200
Matt wrote:
Being the total nerd I am, I was browsing through the GCC 4.1 in-progress ChangeLog: http://gcc.gnu.org/gcc-4.1/changes.html And noticed at the very bottom the inclusion of some stack-smashing and format-string prevention features. Anyone have any thoughts on their implementation?
In 4.1? I will have to look. I sent this out to a different mailing list a few weeks ago, maybe people here will have some answers. This relates to similar changes in gcc/glic instead of kernel level prevention.
----- In version 2.3.4 of glibc... if (__builtin_expect ((uintptr_t) p > (uintptr_t) -size, 0) || __builtin_expect ((uintptr_t) p & MALLOC_ALIGN_MASK, 0)) ^^^ This line was added. There is also a comment on it: + /* Little security check which won't hurt performance: the + allocator never wrapps around at the end of the address space. + Therefore we can exclude some size values which might appear + here by accident or by "design" from some intruder. */ + if (__builtin_expect ((uintptr_t) p > (uintptr_t) -size, 0) + || __builtin_expect ((uintptr_t) p & MALLOC_ALIGN_MASK, 0)) + { + errstr = "free(): invalid pointer"; + errout: + malloc_printerr (check_action, errstr, mem); + return; + } It was mentioned on http://www.securityfocus.com/columnists/359. Now, my questions if some of you can be so kind as to try and answer: In your estimation, how many people actually heard about this (outside the tight circle of secure coding maniacs)? In your estimation, how many people actually go through the pain of upgrading glibc? This seems effective to me. In retrospect, how effective did it prove to be over the past year, in your experience? Is it too early to tell? Heard of this? http://www.cs.ucsb.edu/~wkr/projects/heap_protection/ What's your take on it, and how do you compare the two? I'd appreciate your input if you have the time. Thanks, Gadi. -- http://blogs.securiteam.com/ "Out of the box is where I live". -- Cara "Starbuck" Thrace, Battlestar Galactica.
Current thread:
- gcc 4.1 security features Matt (Feb 16)
- Re: gcc 4.1 security features Gadi Evron (Feb 16)
- Re: gcc 4.1 security features Halvar Flake (Feb 16)
- Re: gcc 4.1 security features Joel Eriksson (Feb 16)
- Re: gcc 4.1 security features Hikaru Gosun (Feb 17)
- Re: gcc 4.1 security features Angelo Dell'Aera (Feb 17)
- RE: gcc 4.1 security features Dave Korn (Feb 18)
- Re: gcc 4.1 security features Matt Conover (Feb 21)
- Re: gcc 4.1 security features Gadi Evron (Feb 16)
- Re: gcc 4.1 security features Eduardo Tongson (Feb 17)
- <Possible follow-ups>
- Re: gcc 4.1 security features Phantasmal Phantasmagoria (Feb 21)