Self-compiled xorg-server 1.20.0 crashes at startup, buffer overflow

[tumtum00]

On 31 July 2018 7:57 PM, Jon Turney wrote:
> > -   Dependencies installed as described in https://x.cygwin.com/docs/cg/prog-build-prerequisites.html, plus xcb-composite-devel
>
> Thanks for pointing out this oversight. I will amend the documentation.

Thanks for that. I typoed the package, it should be libxcb-composite-devel.

> I tried to reproduce this problem by following these steps, but the
> produced executable works ok for me.

I tried 3 new machines today, can reproduce the issue in all of them. All were Win7 x86_64. 2 VMs installed from scratch (one in English, the other German as in my first report) plus a system running on bare metal.

> > #7 0x000000018017e7e9 in __chk_fail () at /usr/src/debug/cygwin-2.10.0-1/newlib/libc/ssp/chk_fail.c:11
> > msg = "*** buffer overflow detected ***: terminated\n"
> > #8 0x000000018018c1c3 in __memcpy_chk (dst=0x60008e570, src=0x45, len=0, slen=0) at /usr/src/debug/cygwin-2.10.0-1/newlib/libc/ssp/memcpy_chk.c:48
>
> This is a wrapper around memcpy, which is being used as we are building
> with _FORTIFY_SOURCE
>
> I'd suggest setting a breakpoint on this line (after installing the
> cygwin-debuginfo package for relevant debug info) and trying to
> understand why it's not succeeding.

Attached the backtrace at memcpy_chk.c:48.
I've been trying to figure out what is going on from the source code, but I'm not really getting anywhere.

Does it suffice to install cygwin-debuginfo or do I need to set something up?
I ran gdb with `set cygwin-exceptions on` too, but no further information came up in the backtrace.

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