caja segfaults while browsing Windows network if a server has an empty name

[Doug Brown]

I am using Ubuntu MATE 16.04.1 LTS with Caja 1.12.7-1.

If a Samba server on the local network has an empty name, caja will segfault in eel_ref_str_ref. To reproduce:

- On a different machine, install samba and manually set its NetBIOS name to an empty string by editing /etc/samba/smb.conf and adding this line under the [global] section:

netbios name = ""

- On the other machine, restart nmbd:

sudo service nmbd restart

- On your computer, run "smbtree -N" to verify that the other machine has an empty name. You should see a line like this, with emptiness after the \\:

\\ ubuntu-mate-2 server (Samba, Ubuntu)

- Now, on your computer, browse to the Windows network in Caja by going to Places -> Network and opening the "Windows Network" folder.

- Open the folder corresponding to the workgroup that the other machine belongs to.

- Caja will segfault.

It's not necessarily uncommon for a server to have an empty name; nmbd used to have a bug that would set the default provided NetBIOS name to an empty string if the computer's hostname was too long.

This exact same problem used to occur in Nautilus until it was fixed last year. See: https://bugs.launchpad.net/ubuntu/+source/nautilus/+bug/1280867

ProblemType: Crash
DistroRelease: Ubuntu 16.04
Package: caja 1.12.7-1
ProcVersionSignature: Ubuntu 4.4.0-31.50-generic 4.4.13
Uname: Linux 4.4.0-31-generic x86_64
ApportVersion: 2.20.1-0ubuntu2.1
Architecture: amd64
CasperVersion: 1.376
CurrentDesktop: MATE
Date: Wed Nov 30 02:02:57 2016
ExecutablePath: /usr/bin/caja
LiveMediaBuild: Ubuntu-MATE 16.04.1 LTS "Xenial Xerus" - Release amd64 (20160719)
ProcCmdline: caja
ProcEnviron:
 PATH=(custom, user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SegvAnalysis:
 Segfault happened at: 0x5601a4d63723 <eel_ref_str_ref+3>: lock addl $0x1,-0x4(%rdi)
 PC (0x5601a4d63723) ok
 source "$0x1" ok
 destination "-0x4(%rdi)" (0xfffffffffffffffc) not located in a known VMA region (needed writable region)!
SegvReason: writing unknown VMA
Signal: 11
SourcePackage: caja
StacktraceTop:
 eel_ref_str_ref ()
 ?? ()
 caja_file_new_from_info ()
 ?? ()
 ?? ()
Title: caja crashed with SIGSEGV in eel_ref_str_ref()
UpgradeStatus: No upgrade log present (probably fresh install)
UserGroups: adm cdrom dip lpadmin plugdev sambashare sudo
XsessionErrors:
 mate-session[5508]: WARNING: Unable to find provider '' of required component 'dock'
 (nm-applet:5733): Gdk-CRITICAL **: gdk_window_thaw_toplevel_updates: assertion 'window->update_and_descendants_freeze_count > 0' failed
 (deja-dup-monitor:5748): GLib-GObject-CRITICAL **: g_object_unref: assertion 'G_IS_OBJECT (object)' failed

[Apport retracing service (apport)]

Thank you for taking the time to report this crash and helping to make this software better. This particular crash has already been reported and is a duplicate of bug #1569132, so is being marked as such. Please look at the other bug report to see if there is any missing information that you can provide, or to see if there is a workaround for the bug. Additionally, any further discussion regarding the bug should occur in the other report. Please continue to report any other bugs you may find.