[Libguestfs] guestfsd crashes when the handle is closed

[Safa Rekik]

Hello,

So in ubuntu1204 guest This is what i got :

    *(gdb)* bt full
   * #0*  0x005a9fc0 in exit () from /lib/i386-linux-gnu/libc.so.6
    No symbol table info available.
  *  #1*  0x0805f7dd in ?? ()
    No symbol table info available.
   * #2*  0x0804aedf in ?? ()
    No symbol table info available.
    *#3*  0x005904d3 in __libc_start_main () from
/lib/i386-linux-gnu/libc.so.6
   No symbol table info available.
   *#4*  0x0804b025 in ?? ()
   No symbol table info available.

i also tried to print information about each frame, i found unknown
addresses in frame 4 and 3, here are the details :
========================================
--frame 4 :
*            (gdb) info frame*
           Stack level 4, frame at 0x0:
          eip = 0x804b025; saved eip 0x804b025
          Outermost frame: outermost
         caller of frame at 0xbfd55210
        Arglist at* unknown address.*
         Locals at* unknown address*, Previous frame's sp in esp
*--*frame 3:
*             (gdb) info frame *
             Stack level 3, frame at 0xbfd55210:
              eip = 0x5904d3 in __libc_start_main; saved eip 0x804b025
             called by frame at 0x0, caller of frame at 0xbfd551a0
            Arglist at *unknown address*.
             Locals at *unknown address*, Previous frame's sp is
0xbfd55210
             Saved registers:
           ebx at 0xbfd551fc, ebp at 0xbfd55208, esi at 0xbfd55200, edi at
           0xbfd55204,
           eip at 0xbfd5520c
=========================================

For fedora 20 guest, this is the back trace output :
=====================================
*(gdb) bt full*
#0  0xb73e2040 in exit () from /lib/libc.so.6
No symbol table info available.
#1  0xb77263a8 in main_loop ()
No symbol table info available.
#2  0xb76fe190 in main ()
No symbol table info available.

*(gdb) frame 0*
#0  0xb73e2040 in exit () from /lib/libc.so.6
(gdb) info frame
Stack level 0, frame at 0xbfb022a0:
 eip = 0xb73e2040 in exit; saved eip 0xb77263a8
 called by frame at 0xbfb02350
 Arglist at 0xbfb02298, args:
 Locals at 0xbfb02298, Previous frame's sp is 0xbfb022a0
 Saved registers:
  eip at 0xbfb0229c

*(gdb) frame 1*
#1  0xb77263a8 in main_loop ()
(gdb) info frame
Stack level 1, frame at 0xbfb02350:
 eip = 0xb77263a8 in main_loop; saved eip 0xb76fe190
 called by frame at 0xbfb025f0, caller of frame at 0xbfb022a0
 Arglist at 0xbfb022ac, args:
 Locals at 0xbfb022ac, Previous frame's sp is 0xbfb02350
 Saved registers:
  ebx at 0xbfb0233c, ebp at 0xbfb02348, esi at 0xbfb02340, edi at
0xbfb02344,
  eip at 0xbfb0234c

*(gdb) frame 2*
#2  0xb76fe190 in main ()
(gdb) info frame
Stack level 2, frame at 0xbfb025f0:
 eip = 0xb76fe190 in main; saved eip 0xb73c9b83
 caller of frame at 0xbfb02350
 Arglist at 0xbfb025e8, args:
 Locals at 0xbfb025e8, Previous frame's sp is 0xbfb025f0
 Saved registers:
  ebx at 0xbfb025dc, ebp at 0xbfb025e8, esi at 0xbfb025e0, edi at
0xbfb025e4,
  eip at 0xbfb025ec
=============================================

As for parallel connections,  we are looking forward for 1.28 :-).
Meanwhile we are trying to test things with a single handle.

Thanks !


2014-05-15 0:16 GMT+02:00 Richard W.M. Jones <rjones at redhat.com>:

> On Wed, May 14, 2014 at 06:07:37PM +0200, Safa Rekik wrote:
> > Hello,
> >
> > I launched guestfsd in my guest with this command : guestfsd* -rv*.
> > When i close the handle the deamon crashes.
> >
> > This is the output i got (Deamon side) :
> >                              guestfsd: main_loop : new request, len 0x28
> >                              fsync /dev/sda
> >                              /dev/sr0 : No medium found
> >                              guestfsd : main_loop : proc 282
> > (internal_autosynx) took 0.19  seconds
> >                              *read: unexpected end of file on fd 3 *
> >
> > I got the same error with both ubuntu12.04 and fedora 20 guests. I know
> > that in ubuntu the guestfsd version is quite but fedora 20 has 1.26
> > libguestfs version i think.
>
> Can you attach a debugger to it and find out where it crashes or
> exits.  Something like:
>
>   # gdb /usr/sbin/guestfsd `pidof guestfsd`
>   (gdb) break exit
>   (gdb) cont
>   ... when it exits ...
>   (gdb) bt
>
> As discussed on IRC, guestfsd is single-threaded at the moment, but
> one of the jobs for 1.28 is to add support for multiple parallel
> connections.
>
> Rich.
>
> --
> Richard Jones, Virtualization Group, Red Hat
> http://people.redhat.com/~rjones
> Read my programming and virtualization blog: http://rwmj.wordpress.com
> virt-p2v converts physical machines to virtual machines.  Boot with a
> live CD or over the network (PXE) and turn machines into KVM guests.
> http://libguestfs.org/virt-v2v
>



-- 

Safa REKIK
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