Re: Kernel update breaks Chez Scheme

[John Reiser <jreiser BitWagon com>]

>>First, try the application under the values 1, 3, 0, 11, and 9 of
>>/proc/sys/kernel/exec-shield, when running 2080_FC5.

> OK. The application works under 0, 1 and 9, but not under 3 or 11. Is
> there documentation for what these new modes do?

The distinguishing bit is the bit with value (1<<1), which sets
noexecstack by default.  It appears that the application wants to
execute instructions from an on-stack [automatic local] array,
but does not have a PT_GNU_STACK segment [<elf.h>] which declares
the requirement for execute permission of the stack region.

You can confirm this diagnosis by running the application under
the gdb debugger.  Looking at the program counter and the memory
layout at the time of the fault.
	(gdb) info reg
	(gdb) info proc  ## note <pid> for use below
	(gdb) shell cat /proc/<pid>/maps

Check the release notes and other documentation on execstack
and setarch.  For example,  http://dag.wieers.com/howto/compatibility/
If the diganosis is correct, then Fedora now considers this case
to be an application bug.

--