dhunt at ucar
Aug 21, 2012, 10:03 AM
Post #6 of 6
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Re: [mp2] mod_perl 2.0.7 Segfault When Loading Certain Perl Module
[In reply to]
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Hi again: Tracking this down further. I noticed that when we build this
apache/mod_perl we had turned off the 'make test' step. Attached is a
formal bug report with debugging enabled for both mod_perl and perl. The
test suite does not even start, as the server segfaults before the tests
can be run.
It still seems to be failing near Perl__invlist_union_maybe_complement_2nd
when compiling a regular expression.
Thanks much,
Doug Hunt
dhunt [at] ucar
Software Engineer
UCAR - COSMIC, Tel. (303) 497-2611
On Mon, 20 Aug 2012, Doug Hunt wrote:
> Hi once more:
>
> I've installed a mod_perl compiled with MP_DEBUG=1 and obtained a core file,
> from which I get this stack trace when loading Carp.pm. It seems
> it segfaults when compiling the regular expression from this line in Carp.pm:
>
> is_utf8($arg) or $arg =~
> s/([[:cntrl:]]|[[:^ascii:]])/sprintf("\\x{%x}",ord($1))/eg;
>
> Does this help at all?
>
> Regards,
>
> Doug Hunt
>
> -------------------%<--------------------------------------------
> (gdb) where
> #0 0x0000000000513346 in Perl__invlist_union_maybe_complement_2nd ()
> #1 0x000000000051642d in S_regclass ()
> #2 0x0000000000518e38 in S_regpiece ()
> #3 0x000000000051ab30 in S_regbranch ()
> #4 0x000000000051ae2d in S_reg ()
> #5 0x0000000000518dae in S_regpiece ()
> #6 0x000000000051ab30 in S_regbranch ()
> #7 0x000000000051ae2d in S_reg ()
> #8 0x000000000051dadc in Perl_re_compile ()
> #9 0x00000000004d2d24 in Perl_pmruntime ()
> #10 0x0000000000506404 in Perl_yyparse ()
> #11 0x00000000005721b0 in S_doeval ()
> #12 0x0000000000573ea9 in Perl_pp_require ()
> #13 0x0000000000489ee1 in modperl_pp_require ()
> #14 0x000000000053fc93 in Perl_runops_standard ()
> #15 0x00000000004dd0c3 in Perl_eval_sv ()
> #16 0x000000000047c3de in modperl_require_module (pv=0x1b8a498 "Carp",
> logfailure=1)
> #17 0x0000000000475e6d in modperl_config_apply_PerlModule (s=0x1b68950,
> scfg=0x1b6ca00, perl=0x1beeb10, p=0x1b5f138)
> #18 0x000000000047322f in modperl_startup (s=0x1b68950, p=0x1b5f138)
> #19 0x0000000000472ee2 in modperl_startup (s=0x1b68950, p=0x1b5f138)
> #20 0x000000000047415b in modperl_init (base_server=0x1b68950, p=0x1b5f138)
> #21 0x0000000000474484 in modperl_hook_init (pconf=0x1b5f138, plog=0x1ba5368,
> ptemp=0x1b69188, s=0x1b68950)
> #22 0x0000000000464701 in ap_run_open_logs ()
> #23 0x000000000044abed in main ()
> ----------------------%<-------------------------------------------------
>
>
>
> dhunt [at] ucar
> Software Engineer
> UCAR - COSMIC, Tel. (303) 497-2611
>
> On Mon, 20 Aug 2012, Doug Hunt wrote:
>
>> Hi Fred, modperl folks:
>>
>> We've narrowed down this bug a bit more. We are currently running perl
>> 5.16.1 (latest), the latest mod_perl from source and apache version 2.2.22.
>>
>> If we run a simple httpd.conf with this line:
>>
>> PerlModule Carp
>>
>> Then single-process startup will fail on the second perl startup.
>> (perl starts up twice when apache is started, as explained in
>> http://perl.apache.org/docs/2.0/user/handlers/server.html).
>>
>> httpd -X
>> (segmentation fault)
>>
>> We can tell that apache starts up perl successfully the first time by
>> running strace. The segfault can be traced to one line in Carp.pm:
>>
>> --------------------%<----------------------------------------------------
>> # Transform an argument to a function into a string.
>> sub format_arg {
>>
>> ...
>>
>> # The following handling of "control chars" is direct from
>> # the original code - it is broken on Unicode though.
>> # Suggestions?
>> is_utf8($arg) or $arg =~
>> s/([[:cntrl:]]|[[:^ascii:]])/sprintf("\\x{%x}",ord($1))/eg;
>> return $arg;
>> }
>>
>> --------------------%<-------------------------------------------------------
>>
>> If we comment out the line which starts 'is_utf8...' then the segfault is
>> prevented. It strikes me as odd that just *compiling* that line (which is
>> legal perl) should cause a segfault, but that is what we repeatedly
>> observe.
>>
>> Any ideas or thoughts welcome!
>>
>> Regards,
>>
>> Doug Hunt
>>
>> dhunt [at] ucar
>> Software Engineer
>> UCAR - COSMIC, Tel. (303) 497-2611
>>
>> On Tue, 14 Aug 2012, Fred Moyer wrote:
>>
>>> Can you try the latest version from source?
>>>
>>> http://perl.apache.org/download/source.html
>>>
>>> It looks like you are using perl 5.16, some recent fixes were
>>> committed there. The subversion tip will likely be the 2.0.8 RC in a
>>> week or so.
>>>
>>> On Mon, Aug 13, 2012 at 3:01 PM, Jason Lin <jasonlin [at] ucar> wrote:
>>>> Hi,
>>>>
>>>> I work for a project that has been using mod_perl for quite a while.
>>>> Recently, we upgraded our 64-bit web server with Perl 5.16, mod_perl
>>>> 2.0.7
>>>> (it's 2.0.6 with patch), and apache 2.2.22 on CentOS 6.3. Since then,
>>>> we've
>>>> been unable to start Apache server (segmentation faults) with same
>>>> httpd.conf which worked previously.
>>>>
>>>> As far as I can tell, the segfault seems to be triggered while trying to
>>>> load any Perl module using either PerlModule directive or in <Perl> block
>>>> in
>>>> httpd.conf that directly or indirectly use Carp, or even just try to load
>>>> Carp itself. Strace shows that the process would segfault while loading
>>>> (or
>>>> right after loading) Carp.pm. The server can still successfully start and
>>>> work when carefully removing such modules in httpd.conf.
>>>>
>>>> Is anyone seeing this same issue or have any ideas how it can be fixed
>>>> other
>>>> than trying to hack through all the Perl modules to make sure Carp is not
>>>> called?
>>>>
>>>>
>>>> perl -V
>>>> Summary of my perl5 (revision 5 version 16 subversion 0) configuration:
>>>>
>>>> Platform:
>>>> osname=linux, osvers=2.6.32-279.1.1.el6.x86_64, archname=x86_64-linux
>>>> uname='linux fox.cosmic.ucar.edu 2.6.32-279.1.1.el6.x86_64 #1 smp tue
>>>> jul 10 13:47:21 utc 2012 x86_64 x86_64 x86_64 gnulinux '
>>>> config_args='-Dprefix=/ops/tools -des
>>>> -Accflags=-DPERL_RELOCATABLE_INCPUSH'
>>>> hint=recommended, useposix=true, d_sigaction=define
>>>> useithreads=undef, usemultiplicity=undef
>>>> useperlio=define, d_sfio=undef, uselargefiles=define, usesocks=undef
>>>> use64bitint=define, use64bitall=define, uselongdouble=undef
>>>> usemymalloc=n, bincompat5005=undef
>>>> Compiler:
>>>> cc='cc', ccflags ='-DPERL_RELOCATABLE_INCPUSH -fno-strict-aliasing
>>>> -pipe
>>>> -fstack-protector -I/usr/local/include -D_LARGEFILE_SOURCE
>>>> -D_FILE_OFFSET_BITS=64',
>>>> optimize='-O2',
>>>> cppflags='-DPERL_RELOCATABLE_INCPUSH -fno-strict-aliasing -pipe
>>>> -fstack-protector -I/usr/local/include'
>>>> ccversion='', gccversion='4.4.6 20120305 (Red Hat 4.4.6-4)',
>>>> gccosandvers=''
>>>> intsize=4, longsize=8, ptrsize=8, doublesize=8, byteorder=12345678
>>>> d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=16
>>>> ivtype='long', ivsize=8, nvtype='double', nvsize=8, Off_t='off_t',
>>>> lseeksize=8
>>>> alignbytes=8, prototype=define
>>>> Linker and Libraries:
>>>> ld='cc', ldflags =' -fstack-protector -L/usr/local/lib'
>>>> libpth=/usr/local/lib /lib/../lib64 /usr/lib/../lib64 /lib /usr/lib
>>>> /lib64 /usr/lib64 /usr/local/lib64
>>>> libs=-lnsl -lgdbm -ldl -lm -lcrypt -lutil -lc
>>>> perllibs=-lnsl -ldl -lm -lcrypt -lutil -lc
>>>> libc=, so=so, useshrplib=false, libperl=libperl.a
>>>> gnulibc_version='2.12'
>>>> Dynamic Linking:
>>>> dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-Wl,-E'
>>>> cccdlflags='-fPIC', lddlflags='-shared -O2 -L/usr/local/lib
>>>> -fstack-protector'
>>>>
>>>>
>>>> Characteristics of this binary (from libperl):
>>>> Compile-time options: HAS_TIMES PERLIO_LAYERS PERL_DONT_CREATE_GVSV
>>>> PERL_MALLOC_WRAP PERL_PRESERVE_IVUV
>>>> PERL_RELOCATABLE_INCPUSH USE_64_BIT_ALL
>>>> USE_64_BIT_INT USE_LARGE_FILES USE_LOCALE
>>>> USE_LOCALE_COLLATE USE_LOCALE_CTYPE
>>>> USE_LOCALE_NUMERIC USE_PERLIO USE_PERL_ATOF
>>>> Built under linux
>>>> Compiled at Aug 1 2012 16:14:39
>>>> %ENV:
>>>> PERL5LIB="/ops/tools/lib"
>>>> @INC:
>>>> /ops/tools/lib
>>>> /ops/tools/lib/perl5/site_perl/5.16.0/x86_64-linux
>>>> /ops/tools/lib/perl5/site_perl/5.16.0
>>>> /ops/tools/lib/perl5/5.16.0/x86_64-linux
>>>> /ops/tools/lib/perl5/5.16.0
>>>> .
>>>>
>>>> Note that we compiled Perl with relocation flag
>>>> (-DPERL_RELOCATABLE_INCPUSH)
>>>> turned on, yet same issue can also be found without the flag in our test.
>>>>
>>>> Any help/advice would be appreciated, thank you in advance.
>>>>
>>>>
>>>> Best,
>>>> Jason
>>>
>>
>
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bug_report.2012.08.21
