From: glaubitz@...
Date: 2016-03-27T17:35:12+00:00
Subject: [ruby-core:74611] [Ruby trunk Bug#12118] ruby2.3: Segfaults on m68k due to improper stack allocation

Issue #12118 has been updated by John Paul Adrian Glaubitz.


I just verified that ruby2.3 works fine on m68k with both the changes from [ruby-core:74537] and in rb_locale_charmap_index applied!

Thanks for fixing this issue. And please make sure to backport the fixes to ruby2.3 so that the next updated Debian upload for ruby2.3 will be automatically fixed!

Again, thanks a lot!

Adrian

----------------------------------------
Bug #12118: ruby2.3: Segfaults on m68k due to improper stack allocation
https://bugs.ruby-lang.org/issues/12118#change-57738

* Author: John Paul Adrian Glaubitz
* Status: Closed
* Priority: Normal
* Assignee: 
* ruby -v: 
* Backport: 2.1: REQUIRED, 2.2: REQUIRED, 2.3: REQUIRED
----------------------------------------
Hello!

On Motorola 680x0, ruby2.2 and ruby2.3 segfault when running the Ruby interpretor:

./miniruby -I./lib -I. -I.ext/common  ./tool/runruby.rb --extout=.ext  -- --disable-gems -r./m68k-linux-gnu-fake ./tool/rbinstall.rb --make="/usr/bin/make" --dest-dir="/<<PKGBUILDDIR>>/debian/tmp" --extout=".ext" --mflags="-w" --make-flags="w -- DESTDIR=/<<PKGBUILDDIR>>/debian/tmp" --data-mode=0644 --prog-mode=0755 --installed-list .installed.list --mantype="doc"
installing binary commands:   /usr/bin
/<<PKGBUILDDIR>>/lib/fileutils.rb:250: [BUG] Segmentation fault at 0x5f583332
ruby 2.3.0p0 (2015-12-25) [m68k-linux-gnu]

This happens while building ruby2.3 on Debian, for example [1].

Andreas Schwab has already investigated into this issue and he came up with the following patch for ruby2.2 [2]:

```diff
Index: ruby-2.2.3/thread_pthread.c
===================================================================
--- ruby-2.2.3.orig/thread_pthread.c
+++ ruby-2.2.3/thread_pthread.c
@@ -678,15 +678,14 @@ reserve_stack(volatile char *limit, size
 	limit += size;
 	if (limit > end) {
 	    size = limit - end;
-	    limit = alloca(size);
+	    limit = alloca(stack_check_margin+size);
 	    limit[stack_check_margin+size-1] = 0;
 	}
     }
     else {
 	limit -= size;
 	if (buf > limit) {
-	    limit = alloca(buf - limit);
-	    limit -= stack_check_margin;
+	    limit = alloca(buf - limit + stack_check_margin);
 	    limit[0] = 0;
 	}
     }
```

The same patch works fine on ruby2.3, I although I had to modify it so it still applies the same way in ruby2.3.
The bug can be reproduced in a qemu-m68k chroot environment which can be set up quite easily [3].

It would be very important for Debian's Motorola 680x0 port to get this issue fixed.

Thanks,
Adrian

> [1] https://buildd.debian.org/status/fetch.php?pkg=ruby2.3&arch=m68k&ver=2.3.0-2&stamp=1455092994
> [2] https://lists.debian.org/debian-68k/2015/11/msg00057.html
> [3] https://wiki.debian.org/M68k/sbuildQEMU



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