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Re: apps built w/ -fstack-protector-all segfault
- From: "Peter S. Mazinger" <ps dot m at gmx dot net>
- To: Eric Christopher <echristo at apple dot com>
- Cc: GCC Development <gcc at gcc dot gnu dot org>
- Date: Tue, 15 Nov 2005 07:56:06 +0100 (CET)
- Subject: Re: apps built w/ -fstack-protector-all segfault
On Mon, 14 Nov 2005, Eric Christopher wrote:
> >
> >> apps built w/ -fstack-protector-all segfault
> >
> > You will have to give us more info. Most gcc developers probably
> > don't have a copy of UClibc, and plus it sounds like you have made
> > gcc changes that weren't included in your message. So there isn't
> > much we can do here except ask for more details. Try debugging the
> > problem. If you can identify a specific problem here, and give us
> > details about it, we can probably help.
>
> Also since __builtin_trap is used in the fail mechanism the comment
> above the trap instruction in i386.md might be useful:
This is only true is libssp.so is used, I am using "established, working"
exit code, that worked w/ earlier ssp as well (when it was not
integrated) I mentioned that I use it as integrated into libc (exactly
like glibc-cvs does), glibc uses libc_message iirc for exit.
this should also influence the -fstack-protector behaviour, but that seems
to be OK.
__builtin_trap is used as I can see only if a vulnerability is found, this
happens though on a simple hello world.
Thanks, Peter
>
> ;; We used to use "int $5", in honor of #BR which maps to interrupt
> vector 5.
> ;; That, however, is usually mapped by the OS to SIGSEGV, which is often
> ;; caught for use by garbage collectors and the like. Using an insn
> that
> ;; maps to SIGILL makes it more likely the program will rightfully die.
> ;; Keeping with tradition, "6" is in honor of #UD.
>
> So you may be seeing something mapped odd, or...
>
> -eric
>
>
--
Peter S. Mazinger <ps dot m at gmx dot net> ID: 0xA5F059F2
Key fingerprint = 92A4 31E1 56BC 3D5A 2D08 BB6E C389 975E A5F0 59F2