[ILUG] Can anyone see any reason why a customer would need to compile a new compiler?

[Brian Foster]

  | Date: Sat, 24 Jun 2006 19:04:19 +0100 (IST)
  | From: paul at clubi.ie
  | 
  |[... gcc's SSP (also called "ProPolice") is ] simply the insertion
  | of guard values in the frame 'preamble' to protect the return address
  | by overflow of variables local to the frame - by having the compiler
  | emit code to check the guard is still valid when returning from a
  | function.

 and the rearrangement of local (auto) variables,
 and the duplication of certain parameters; see
  http://www.trl.ibm.com/projects/security/ssp/
 or (horribly long url)
  https://buildsecurityin.us-cert.gov/daisy/bsi/articles/knowledge/coding/310.html?branch=1&language=1

  | (Note that if the guard is a well-known value, and the attacker can
  | inject full values (rather than say, ASCII restricted ones), the
  | attacker can defeat SSP easily. I guess though compilers can easily
  | randomise the guard value somewhat on a per-object file basis.).

 yes.  the value, sometimes called a canary, is
 nominally random (per execution, not per compile),
 albeit there is a fixed fallback.

cheers!
	-blf-
-- 
Experienced (20+ yrs) kernel/software Eng: | Brian Foster   Montpellier,
 • Unix, embedded, &tc;  • Linux;  • doc;  | blf at utvinternet.ie   FRANCE
 • IDL, automated testing, process, &tc.   |  Stop E$$o (ExxonMobile)!
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