[libavg-devel] Ubuntu 8.04: libavg SIGSEGV on pyscript termination

[Ulrich von Zadow]

Hi,

we are not the only ones with this problem:

http://ubuntuforums.org/showthread.php?t=762228

OXullo Intersecans wrote:
> On Ubuntu 8.04 libavg causes segmentation faults at *each* script exit.
> This is due to libselinux1 which is the apparent responsible of the  
> problem.
> 
> Workaround at tail.
> 
> 
> Simplest testcase:
> 
> 1. install python-libavg w/ deps (packaged hardy/universe or svn r:2885)
> 2. from python cli:
>  >>> import libavg
>  >>> CTRL-D
> 
> 
> distro: Ubuntu hardy heron / 8.04
> arch: both i386 (Intel core duo) and amd64 (AMD Athlon64 X2)
> 
> libselinux1:
>    Installed: 2.0.55-0ubuntu4
>    Candidate: 2.0.55-0ubuntu4
>    Version table:
>       2.0.55-0ubuntu4 0
>          500 http://de.archive.ubuntu.com hardy/main Packages
>   *** 2.0.55-0ubuntu4 0
>          100 /var/lib/dpkg/status
> 
> python-libavg:
>    Installed: 0.7.0-4ubuntu1
>    Candidate: 0.7.0-4ubuntu1
>    Version table:
>   *** 0.7.0-4ubuntu1 0
>          500 http://de.archive.ubuntu.com hardy/universe Packages
>          100 /var/lib/dpkg/status
> 
> Valgrind reports:
> 
> =29183== Invalid read of size 8
> ==29183== at 0xE29B9DD: fini_context_translations (setrans_client.c:211)
> ==29183== by 0xE28F1F1: (within /lib/libselinux.so.1)
> ==29183== by 0xE29D040: (within /lib/libselinux.so.1)
> ==29183== by 0x570010F: exit (exit.c:75)
> ==29183== by 0x56E91CA: (below main) (libc-start.c:252)
> ==29183== Address 0x80 is not stack'd, malloc'd or (recently) free'd
> ==29183==
> ==29183== Process terminating with default action of signal 11  
> (SIGSEGV): dumping core
> ==29183== Access not within mapped region at address 0x80
> ==29183== at 0xE29B9DD: fini_context_translations (setrans_client.c:211)
> ==29183== by 0xE28F1F1: (within /lib/libselinux.so.1)
> ==29183== by 0xE29D040: (within /lib/libselinux.so.1)==29183== by  
> 0x570010F: exit (exit.c:75)
> ==29183== by 0x56E91CA: (below main) (libc-start.c:252)
> 
> gdb says:
> 
> Program received signal SIGSEGV, Segmentation fault.
> [Switching to Thread 0x7f3af10916e0 (LWP 15047)]
> 0x00007f3ae812a9dd in fini_context_translations () at setrans_client.c: 
> 211
> 211 free(prev_r2t_trans);
> (gdb) bt
> #0 0x00007f3ae812a9dd in fini_context_translations () at  
> setrans_client.c:211
> #1 0x00007f3ae811e1f2 in __do_global_dtors_aux () from /lib/ 
> libselinux.so.1
> #2 0x00007ffff9097700 in ?? ()
> #3 0x00007f3ae812c041 in _fini () from /lib/libselinux.so.1
> #4 0x00007ffff9097700 in ?? ()
> #5 0x00007f3af0e88796 in _dl_fini () from /lib64/ld-linux-x86-64.so.2
> Backtrace stopped: previous frame inner to this frame (corrupt stack?)
> 
> 
> NOTES:
> 
> src/setrans_client.c:209 (libselinux1-2.0.55 source)
> --------------------------------------
> hidden void fini_context_translations(void)
> {
>          free(prev_r2t_trans);
>          free(prev_r2t_raw);
>          free(prev_t2r_trans);
>          free(prev_t2r_raw);
> }
> 
> This function is called at exit, libselinux patches every execve().  
> Without selinux package this low-level framework seems to be quite  
> useless, but still unremovable, due to several dependencies and kernel  
> design (I suppose. Any clues?)
> Any line of code contained in this function causes segfault, don't be  
> fouled by a simple free() fuss.
> 
> 
> **** Workaround: disable SETRANS
> 
> $ apt-get source libselinux1
> $ cd libselinux-2.0.55
> $ DISABLE_SETRANS=y dpkg-buildpackage -rfakeroot -uc -b
> $ cd ..
> $ sudo dpkg -i libselinux1_2.0.55-0ubuntu4_amd64.deb (or i386 one)
> 
> ( launchpad ref: https://bugs.launchpad.net/ubuntu/+source/libselinux/+bug/237156 
>   )
> 
> 
> 
> --
> OXullo Intersecans
> 
> 0 2 L > Outside Standing Level
> http://www.02L.net
> 
> 
> 
> 
> 
> _______________________________________________
> libavg-devel mailing list
> libavg-devel at datenhain.de
> https://mail.datenhain.de/mailman/listinfo/libavg-devel
> 


-- 
Any technology distinguishable from magic is insufficiently advanced.

Ulrich von Zadow | +49-172-7872715
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