GNU bug report logs - #15793
Bug: linking shared libraries on Cygwin results in undefined references to __stack_chck_guard for code compiled with -fstack-protector

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Richard PALO <richard.palo <at> free.fr>
To: bug-libtool <at> gnu.org
Cc: libtool-patches <at> gnu.org
Subject: Re: Bug: linking shared libraries on Cygwin results in undefined
 references to __stack_chck_guard for code compiled with -fstack-protector
Date: Sat, 02 Nov 2013 23:45:29 +0100

Le 02/06/10 05:24, Yaakov (Cygwin/X) a écrit :
> On Sat, 15 May 2010 09:07:49 +0200
> Bart Van Assche <bvanassche <at> acm.org> wrote:
>> This behavior has been observed with libtool version 2.2.6.
>
> Bug confirmed.  When code is compiled with -fstack-protector{,-all},
> GCC "emits extra code to check for buffer overflows, such as stack
> smashing attacks".  This extra code uses symbols from libssp, and
> therefore (at least) Cygwin's GCC specs contain:
>
> *link_ssp:
> %{fstack-protector|fstack-protector-all:-lssp_nonshared -lssp}
>
> Therefore, when libtool fails to pass -fstack-protector{,-all} at link
> stage, the link fails.
>
> Patch attached.  (Yes, I have a copyright assignment on file.)
>
>
> Yaakov
> Cygwin/X
>

I've done some limited testing of this patch on a SunOS distro with 
pkgsrc, and it certainly helps a number of cases since it is gcc that 
generates the necessary '-lssp_nonshared -lssp' libs for linking (at 
least in absence of '-nostdlib').

Please include in the upcoming version.

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