Re: Cyg32 on Win64 fails with stack-protector

[Corinna Vinschen <corinna-cygwin@cygwin.com>]

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On May 31 09:13, Ken Brown wrote:
> On 5/31/2018 4:18 AM, Corinna Vinschen wrote:
> > On May 30 19:29, Bill Zissimopoulos wrote:
> > > Corinna, thanks for your response.
> > > 
> > > On 5/29/18, 9:59 AM, Corinna Vinschen wrote:
> > > 
> > > > Hi Ben,
> > > > 
> > > > On Apr 27 19:12, Ben RUBSON wrote:
> > > > > Hi,
> > > > > 
> > > > > We are facing an issue with Cygwin 2.10 32 bits running on Windows 64
> > > > > bits.
> > > > > 
> > > > > Issue was found running EncFS FUSE FS using WinFsp.
> > > > > 
> > > > > When forking, and calling StartServiceCtrlDispatcher, program fails with
> > > > > 0xC0000028 / STATUS_BAD_STACK.
> > > > > 
> > > > > Testing several Cygwin versions reveals that issue was introduced
> > > > > between
> > > > > 2017-11-14 and 2017-12-01.
> > > > > And Bill (WinFsp author) found that compiling with -fno-stack-protector
> > > > > works around the issue.
> > > > > 
> > > > > There you can then find the full story and Bill's nice investigation :
> > > > > https://github.com/billziss-gh/winfsp/issues/161
> > > > > 
> > > > > Could it be possible something went wrong with Cygwin ?
> > > > > 
> > > > > Thank you very much for your support !
> > > > 
> > > > Even with Bill's additionl info I have no idea what change in the
> > > > above time frame might be the culprit, especially since no change
> > > > has been made to stack handling.
> > > > 
> > > > I suggest to build your own Cygwin and bisect it.  Also, you
> > > > may want to run your stuff under GDB and set breakpoints to, e.g.,
> > > > Cygwin's exception::handle method.  Make sure the cygwin1.dbg
> > > > file can be found by GDB.
> > > 
> > > There appear to be some SSP related commits in the discussed time frame.
> > > For example:
> > > 
> > > https://sourceware.org/git/?p=newlib-cygwin.git;a=commitdiff;h=0a5dfdbd1ba3
> > > 663a54fa1a7de1a6c4a0a3316a6e
> > > 
> > > Another possibility would be a change in the gcc default options between
> > > Cygwin 2.9 and Cygwin 2.10. I do not know if this is possible, but perhaps
> > > gcc in 2.9 compiles with -fstack-protector disabled by default and gcc in
> > > 2.10 compiles with it enabled by default?
> > > 
> > > Bill
> > 
> > I CCed Ken (gcc) and Yaakov (SSP) to get more qualified input than
> > my own Cygwin DLL centric view.
> 
> I think you meant to CC a different Ken.

Oops, I meant to CC a JonY, in fact, not a Ken at all.  Sorry!


Corinna

-- 
Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Maintainer                 cygwin AT cygwin DOT com
Red Hat

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