[Bug c/37001] New: Uninitialized static variables on x86_64

["gerald at wireshark dot org" <gcc-bugzilla at gcc dot gnu dot org>]

Wireshark's Buildbot system recently uncovered what appears to be a bug in gcc.
The following code:

    static guint                tap_current=0;
    [ ... ]
    fprintf(stderr, "dissect_bssmap tap_current: %u\n", tap_current);

produces the following output:

dissect_bssmap tap_current: 2801996644

'gcc -v' output:
Using built-in specs.
Target: x86_64-linux-gnu
Configured with: ../src/configure -v
--enable-languages=c,c++,fortran,objc,obj-c++,treelang --prefix=/usr
--enable-shared --with-system-zlib --libexecdir=/usr/lib
--without-included-gettext --enable-threads=posix --enable-nls
--with-gxx-include-dir=/usr/include/c++/4.1.3 --program-suffix=-4.1
--enable-__cxa_atexit --enable-clocale=gnu --enable-libstdcxx-debug
--enable-mpfr --enable-checking=release x86_64-linux-gnu
Thread model: posix
gcc version 4.1.3 20070929 (prerelease) (Ubuntu 4.1.2-16ubuntu2)

(I realize this may be an Ubuntu-specific bug. Launchpad.net pointed me here.)

Steps to reproduce:

  Download a recent Wireshark tarball from 
  http://www.wireshark.org/download/automated/src/ or check out from SVN at
  http://anonsvn.wireshark.org/wireshark/trunk/

  Apply the patch which I'll attach shortly and build Wireshark

  Download the capture file from
 
http://www.wireshark.org/download/automated/captures/fuzz-2008-07-31-3587.pcap

  Run './tshark -nVr /tmp/fuzz-2008-07-31-3587.pcap > /dev/null 2> /tmp/tp.out
; head -10 /tmp/tp.out'

You should see something like the following:

dissect_bssmap tap_current: 2801996644
dissect_bssmap tap_current: 0
dissect_bssmap tap_current: 1
dissect_dtap tap_current: 2801996612
dissect_bssmap tap_current: 2
dissect_dtap tap_current: 0
dissect_bssmap tap_current: 3
dissect_dtap tap_current: 1
dissect_bssmap tap_current: 0
dissect_bssmap tap_current: 1

Sorry I don't have a smaller test case.


-- 
           Summary: Uninitialized static variables on x86_64
           Product: gcc
           Version: 4.1.3
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: gerald at wireshark dot org
 GCC build triplet: x86_64-linux-gnu
  GCC host triplet: x86_64-linux-gnu
GCC target triplet: x86_64-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37001