emacs20 segfault: glibc problem?

[Rob Browning <rlb@cs.utexas.edu>]

I mailed a bug report to the emacs bug list last week, and RMS got
back to me suggesting that it just sounded to him like a glibc bug.
So I'd like to see what you think, and if you think it's a glibc bug
too, I'll reassign it to libc6.

Here's the info:

Recently emacs20 has started segfaulting on exit (actually it looks
like it *is*, in fact, calls to exit() that are causing the segfault
-- gdb trace below).  This is most easily demonstrated with "emacs
--help".  The same binary worked just fine a few weeks ago, so the
suspicion is that newer version of glibc have changed some semantics
that are causing the problem.

Here's the failure

  $ emacs --help
  Usage: emacs [-t term] [--terminal term]  [-nw] [--no-windows]  [--batch]
        [-q] [--no-init-file]  [-u user] [--user user]  [--debug-init]
        [--unibyte] [--multibyte] [--version] [--no-site-file]
        [-f func] [--funcall func]  [-l file] [--load file]  [--insert file]
        [+linenum] file-to-visit  [--kill]
  Report bugs to bug-gnu-emacs@gnu.org.  First, please see
  the Bugs section of the Emacs manual or the file BUGS.
  Segmentation fault

Here's the backtrace:

  (gdb) run --help
  Starting program: /home/debian/devel/emacs20/emacs20/src/emacs --help
  Usage: /home/debian/devel/emacs20/emacs20/src/emacs [-t term] [--terminal term]  [-nw] [--no-windows]  [--batch]
        [-q] [--no-init-file]  [-u user] [--user user]  [--debug-init]
        [--unibyte] [--multibyte] [--version] [--no-site-file]
        [-f func] [--funcall func]  [-l file] [--load file]  [--insert file]
        [+linenum] file-to-visit  [--kill]
  Report bugs to bug-gnu-emacs@gnu.org.  First, please see
  the Bugs section of the Emacs manual or the file BUGS.
  Program received signal SIGSEGV, Segmentation fault.
  0x40248a88 in chunk_free () from /lib/libc.so.6
  (gdb) where
  #0  0x40248a88 in chunk_free () from /lib/libc.so.6
  #1  0x40248a2a in free () from /lib/libc.so.6
  #2  0x402104bf in exit () from /lib/libc.so.6
  #3  0x8093430 in main (argc=2, argv=0xbffff504, envp=0xbffff510) at emacs.c:803

The relevant versions of things:

  emacs: 20.3 (Debian package emacs20-20.3-7)
  glibc: 2.1.1 (Debian package libc6-2.2.1-9)
  linux kernel: 2.2.6 (i686)

Let me know if you need any more information, if I can run any tests,
or if I can otherwise help.

Thanks

-- 
Rob Browning <rlb@cs.utexas.edu> PGP=E80E0D04F521A094 532B97F5D64E3930