Bug#787493: FTBFS with GCC 5 and Perl 5.22

2015-06-02 Thread Roderich Schupp
Source: libapache2-mod-perl2
Version: 2.0.9~rc2-1
Severity: serious
Justification: fails to build from source (but built successfully in the past)

Building with GCC 5 and Perl 5.22 (also built with GCC 5) from experimental.
Build stops with


[warning] setting ulimit to allow core files
ulimit -c unlimited; /usr/bin/perl /raid/build/work/libapache2-mod-
perl2-2.0.9~rc2/t/TEST -httpd_conf '/raid/build/work/libapache2-mod-
perl2-2.0.9~rc2/debian/apache2.conf' -bugreport -verbose=1
AH00558: apache2: Could not reliably determine the server's fully qualified
doma
in name, using 127.0.1.1. Set the 'ServerName' directive globally to suppress
this message
(2)No such file or directory: AH02291: Cannot access directory
'/raid/build/work/libapache2-mod-perl2-2.0.9~rc2/t/logs/' for main error log
AH00014: Configuration check failed
/usr/sbin/apache2  -d /raid/build/work/libapache2-mod-perl2-2.0.9~rc2/t -f
/raid/build/work/libapache2-mod-perl2-2.0.9~rc2/t/conf/httpd.conf -D APACHE2 -D
APACHE2_4 -D PERL_USEITHREADS
using Apache/2.4.12

waiting 300 seconds for server to start: .[Mon Jun 01 22:31:36.041661 2015]
[env:warn] [pid 15692:tid 140437197727616] AH01506: PassEnv variable
LD_LIBRARY_PATH was undefined
Segmentation fault (core dumped)
[  error] oh golly, server dumped core

Running under gdb shows:

Program received signal SIGSEGV, Segmentation fault.
0x735f89ce in modperl_env_init () at modperl_env.c:639
639 StructCopy(MP_vtbl_env, PL_vtbl_env, MGVTBL);
(gdb) b modperl_env_init
Breakpoint 1 at 0x735f88e0: file modperl_env.c, line 635.
(gdb) l
634 /* save originals */
635 StructCopy(PL_vtbl_env, MP_PERL_vtbl_env, MGVTBL);
636 StructCopy(PL_vtbl_envelem, MP_PERL_vtbl_envelem, MGVTBL);
637
638 /* replace with our versions */
639 StructCopy(MP_vtbl_env, PL_vtbl_env, MGVTBL);
640 StructCopy(MP_vtbl_envelem, PL_vtbl_envelem, MGVTBL);
641 }
642
643 void modperl_env_unload(void)

StructCopy(src, dst, type) from Perl API essentially does *dst = *src.
In line 639 the destination is PL_vtbl_env which is #define'd
as some element of the array PL_magic_vtables from Perl internals
(I checked that it's index is well within the bounds of the array)

(gdb) whatis PL_magic_vtables
type = const MGVTBL [31]

Note the const here!

(gdb) info symbol PL_magic_vtables
PL_magic_vtables in section .data.rel.ro of /usr/lib/x86_64-linux-
gnu/libperl.so.5.22

So, GCC has put PL_magic_vtables into a read-only section,
hence trying to write to it deservedly produces a segfault.

Cheers, Roderich





-- Package-specific info:

-- System Information:
Debian Release: stretch/sid
  APT prefers wily
  APT policy: (500, 'wily'), (500, 'buildd-unstable'), (500, 'unstable'), (1, 
'buildd-experimental'), (1, 'experimental')
Architecture: amd64 (x86_64)
Foreign Architectures: i386

Kernel: Linux 4.1.0-rc6 (SMP w/4 CPU cores)
Locale: LANG=en_US.utf8, LC_CTYPE=en_US.utf8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)

-- no debconf information


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Bug#787493: FTBFS with GCC 5 and Perl 5.22

2015-06-02 Thread Dominic Hargreaves
Control: severity -1 important
Control: user debian-p...@lists.debian.org
Control: usertags -1 perl-5.22-transition
Control: retitle -1 libapache2-mod-perl2: FTBFS with Perl 5.22

On Tue, Jun 02, 2015 at 10:43:02AM +0200, Roderich Schupp wrote:
 Source: libapache2-mod-perl2
 Version: 2.0.9~rc2-1
 Severity: serious
 Justification: fails to build from source (but built successfully in the past)
 
 Building with GCC 5 and Perl 5.22 (also built with GCC 5) from experimental.

Hi,

Thanks for the report. I can confirm the problem using just perl 5.22
and not GCC 5.

However as this is only reproducible on experimental, I'm downgrading
the severity of this bug report for now.

Cheers,
Dominic.


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