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Re: things to do for arch maintainers

From: Roland McGrath <roland at redhat dot com>
To: Steven Munroe <munroesj at us dot ibm dot com>
Cc: Jakub Jelinek <jakub at redhat dot com>,Ulrich Drepper <drepper at redhat dot com>,GNU libc hacker <libc-hacker at sources dot redhat dot com>
Date: Tue, 20 Dec 2005 15:58:13 -0800 (PST)
Subject: Re: things to do for arch maintainers

> This may be appropriate because powerpc does not have a pc relative 
> reference to access __pointer_chk_guard_local and access via the 
> .got/.toc will fail if access is attemped before the got/toc are 
> relocated. But I wanted to verify this.

If you cannot access it safely in the first _dl_catch_error call in
startup, then leave the macros undefined.  I think the ld.so bootstrap
relocation will be complete before it's ever used.

> It is not clear what this change is really for, so it is difficult to 
> determine what is intended or required.

They make it harder to exploit buffer overruns to write useful addresses
into jmp_buf's PC values and have those result in attacker-chosen jumps.


Thanks,
Roland

References:
- Re: things to do for arch maintainers
  - From: Steven Munroe

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