This is the mail archive of the
cygwin-developers
mailing list for the Cygwin project.
RE: Cyg32 on Win64 fails with stack-protector
- From: "Carter, Mark Andrew (Andy)" <andy dot carter at flightsafety dot com>
- To: "cygwin-developers at cygwin dot com" <cygwin-developers at cygwin dot com>
- Cc: Yaakov Selkowitz <yselkowi at redhat dot com>
- Date: Mon, 25 Jun 2018 15:35:47 +0000
- Subject: RE: Cyg32 on Win64 fails with stack-protector
- References: <8A9D918F-F233-48DA-9B98-B87D7B188C21@gmail.com> <20180529165958.GK3501@calimero.vinschen.de> <DDEADFF6-DFDE-4885-8134-7E6937B86C2A@gmail.com> <20180625094448.GF28757@calimero.vinschen.de>
We use Cyg32 on a Win64 system and have encountered a gcc compiler bug causing stack corruption due to an invalid optimized stack allocation for a function call that return a large structure (40 bytes). Possibly related to the long standing bug reported here "https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83116". This bug could bite with compiler version / switch settings or otherwise valid code changes.
Andy Carter - Senior Staff Software Engineer
FVS - FVS Engineering - 5695 Campus Parkway - Hazelwood, MO, 63042 - United States
Tel: 314.551.8573
Andy.Carter@FlightSafety.com - flightsafety.com - A Berkshire Hathaway company
-----Original Message-----
From: cygwin-developers-owner@cygwin.com [mailto:cygwin-developers-owner@cygwin.com] On Behalf Of Corinna Vinschen
Sent: Monday, June 25, 2018 4:45 AM
To: cygwin-developers@cygwin.com
Cc: Yaakov Selkowitz <yselkowi@redhat.com>
Subject: Re: Cyg32 on Win64 fails with stack-protector
Yaakov, can you take a look, please?
Thanks,
Corinna
On Jun 23 15:50, Ben RUBSON wrote:
> On 29 May 2018 18:59, Corinna Vinschen wrote:
>
> > I suggest to build your own Cygwin and bisect it.
>
> So I tried to bisect and had some difficulties.
> I used a fresh 32 bits installation on a 64 bits system and followed
> this howto :
> https://cygwin.com/faq/faq.html#faq.programming.building-cygwin
>
> Prior to this commit : 6a848db44242a24d6570ef7994918c66ce483fd2
> 2017-11-29 - Yaakov Selkowitz - cygwin: export SSP functions (which is
> the one JonY suspects)
>
> With gcc 7.3, compilation fails with undefined __stack_chk_fail,
> __stack_chk_guard etc...
> With gcc 6.4, compilation succeeds. Cygwin correctly starts with the
> new cygwin1.dll, but then, some programs, such as cmake (cmake --help)
> do not show any output anymore.
> Same behavior using Cygwin snapshots. As it worked a few weeks ago, I
> tried to downgrade some runtime libraries, but with no luck.
> This is easily reproductible, just install Cygwin32 on a 64-bits
> system, and select Cygwin 2.9 library instead of the 2.10 one.
>
> So, unfortunately, I was not able to test any commit prior to the one
> given above.
> This commit however correctly compiles with both gcc 6.4 and 7.3.
> Cygwin correctly starts with it, program correctly show their output.
> And I'm able to reproduce the issue I opened this topic for.
> So something important has changed between 2017-11-14 and 2017-11-29
> which triggers this bug.
>
> Perhaps the new SSP mechanism is more powerful than the previous one
> and triggers a long-time existing bug ?
>
> Thank you again,
>
> Ben
--
Corinna Vinschen Please, send mails regarding Cygwin to
Cygwin Maintainer cygwin AT cygwin DOT com
Red Hat