[libvirt-php] libvirt_domain_interface_addresses causing segfault

[Fernando Casas Schössow]

I think I found the problem and it seems to affect only Windows guests. 
I'm not sure about the cause tough.

Possible causes:

1- Network interface names containing white spaces.
2- One of the interfaces not reporting a MAC address.

As an example here is the output of the equivalent virsh command for a 
Windows guest:

 Name MAC address Protocol Address
-------------------------------------------------------------------------------
 Ethernet 2 52:54:00:99:b5:62 ipv6 fe80::71fd:2467:8755:cb0b%13/64
 Ethernet 2 52:54:00:99:b5:62 ipv4 192.168.0.77/26
 Loopback Pseudo-Interface 1 ipv6 ::1/128
 Loopback Pseudo-Interface 1 ipv4 127.0.0.1/8
 isatap.{974B556C-9BAF-4A84-A1B1-9D1FDABEC29B} 00:00:00:00:00:00 ipv6 
fe80::5efe:192.168.7.21%12/128

Please note the name containing white spaces: "Ethernet 2", "Loopback 
Pseudo-Interface 1". And also interface "Loopback Pseudo-Interface 1" 
not reporting a MAC address.

Hope this additional information helps.

Thanks.

Fernando

On mié, abr 15, 2020 at 11:41 PM, Fernando Casas Schössow 
<casasfernando at outlook.com> wrote:
> Hi,
> 
> While executing libvirt_domain_interface_addresses() with the 
> qemu-agent running in the guest as the source, the function causes 
> PHP to segfault. If I change the source to either dhcp or arp, the 
> function executes correctly.
> 
> Example:
> 
> $netdetails = libvirt_domain_interface_addresses($vmres, 0); <-- 
> executes correctly (dhcp source)
> $netdetails = libvirt_domain_interface_addresses($vmres, 1); <-- 
> segfault (qemu agent source)
> $netdetails = libvirt_domain_interface_addresses($vmres, 2); <-- 
> executes correctly (arp source)
> 
> I tested the equivalent function using virsh against the same host 
> and it executes correctly with any source.
> I have a php-cgi core file that I can share if that may help on 
> finding the problem.
> 
> gdb output:
> 
> GNU gdb (Debian 9.1-2) 9.1
> Copyright (C) 2020 Free Software Foundation, Inc.
> License GPLv3+: GNU GPL version 3 or later 
> <http://gnu.org/licenses/gpl.html>
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> Type "show copying" and "show warranty" for details.
> This GDB was configured as "x86_64-linux-gnu".
> Type "show configuration" for configuration details.
> For bug reporting instructions, please see:
> <http://www.gnu.org/software/gdb/bugs/>.
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>     <http://www.gnu.org/software/gdb/documentation/>.
> 
> For help, type "help".
> Type "apropos word" to search for commands related to "word"...
> Reading symbols from /usr/bin/php-cgi...
> (No debugging symbols found in /usr/bin/php-cgi)
> [New LWP 2594]
> [Thread debugging using libthread_db enabled]
> Using host libthread_db library 
> "/lib/x86_64-linux-gnu/libthread_db.so.1".
> Core was generated by `php-cgi index.php'.
> Program terminated with signal SIGSEGV, Segmentation fault.
> #0 __strlen_sse2 () at ../sysdeps/x86_64/multiarch/../strlen.S:85
> 85	../sysdeps/x86_64/multiarch/../strlen.S: No such file or directory.
> (gdb) bt
> #0 __strlen_sse2 () at ../sysdeps/x86_64/multiarch/../strlen.S:85
> #1 0x000055c6a4ceacd2 in add_assoc_string_ex ()
> #2 0x00007f4d36175253 in ?? () from 
> /usr/lib/php/20180731/libvirt-php.so
> #3 0x000055c6a4d6b477 in execute_ex ()
> #4 0x000055c6a4d705c7 in zend_execute ()
> #5 0x000055c6a4ce8ed4 in zend_execute_scripts ()
> #6 0x000055c6a4c8be38 in php_execute_script ()
> #7 0x000055c6a4b53da8 in ?? ()
> #8 0x00007f4d39efce0b in __libc_start_main (main=0x55c6a4b51cf0, 
> argc=2, argv=0x7fff35718588, init=<optimized out>, fini=<optimized 
> out>,
>     rtld_fini=<optimized out>, stack_end=0x7fff35718578) at 
> ../csu/libc-start.c:308
> #9 0x000055c6a4b544ca in _start ()
> 
> 
> System information:
> 
> OS: Debian Bullseye
> PHP version (fast cgi): 7.3.15
> Libvirt PHP version: 0.5.5
> Libvirt version: 6.0.0
> 
> KVM host libvirt version: 5.9.0
> 
> If you need any other information please let me know.
> 
> Thanks.
> 
> Fernando