VBoxClient crashes on Luuntu 14.04 after updating from 6.1.2 to 6.1.4 (fixed in 6.1.6)

[Gabri74]

After updating guest additions from 6.1.2 to 6.1.4 VboxClient will always crash at boot, causing the system crash report to open with the message:

VBoxClient crashed with SIGSEGV in XQueryExtension()

Host: Ubuntu 19.10 and Windows 10 Guest: Lubuntu 14.04

[Gabri74]

vbox log

[Gabri74]

Lubuntu crash report

[Gabri74]

Only cut&past integration seems affected, all other guest features seem to work..

Running VBoxClient istances after crash:

user      1890  0.0  0.0  54360   372 ?        S    12:03   0:00 /usr/bin/VBoxClient --display
user      1891  0.0  0.0  54508  3564 ?        S    12:03   0:00 /usr/bin/VBoxClient --display
user      1897  0.0  0.0  54360   376 ?        S    12:03   0:00 /usr/bin/VBoxClient --seamless
user      1898  0.0  0.0 186612  3032 ?        Sl   12:03   0:00 /usr/bin/VBoxClient --seamless
user      1906  0.0  0.0  54360   376 ?        S    12:03   0:00 /usr/bin/VBoxClient --draganddrop
user      1907  0.1  0.0 187128  3000 ?        Sl   12:03   0:01 /usr/bin/VBoxClient --draganddrop
user      1913  0.0  0.0  54360  1504 ?        S    12:03   0:00 /usr/bin/VBoxClient --vmsvga-x11
root      2523  0.0  0.0 371428  2888 ?        Sl   12:04   0:00 /usr/sbin/VBoxService --pidfile /var/run/vboxadd-service.sh

[Frank Batschulat (Oracle)]

similar report for 6.1.4 here with a ArchLinux guest:

​https://bbs.archlinux.org/viewtopic.php?id=253089

[Frank Batschulat (Oracle)]

Replying to Gabri74:

Only cut&past integration seems affected, all other guest features seem to work..

That one, the broken cut&paste, is a different bug:

Ticket #19336 (new defect) Linux guest: shared clipboard doesn't work (on fresh VirtualBox-6.1.4-136177)

[Gabri74]

Manually downgrading to 6.1.2 solves the problem

[nixuser]

Same problem has been reported against Fedora 31, Fedora Rawhide and Fedora 32 Beta branch.

​https://bugzilla.redhat.com/show_bug.cgi?id=1806778

[sergiomb]

this happens only with Settings -> display -> graphics controller -> VBoxSVGA ?

[nixuser]

@sergiomb also happens with VBoxVGA.

VMSVGA fixes the crashing problem [for me] but doesn't work for other reasons. I have never managed to get VMSVGA to work on Fedora, I am stuck with a text boot (which I don't care about really) but also an 800x600 display which is of course unusable these days.

[nixuser]

@sergiomb I spoke too soon, I am seeing the crashes in VMSVGA mode now as well.

[Frank Batschulat (Oracle)]

Replying to nixuser:

Same problem has been reported against Fedora 31, Fedora Rawhide and Fedora 32 Beta branch.

​https://bugzilla.redhat.com/show_bug.cgi?id=1806778

For the record, the reported stack trace in there is:

Feb 25 08:12:28 luks systemd[1]: Started Process Core Dump (PID 1478/UID 0).
Feb 25 08:12:29 luks abrt-notification[1480]: Process 1093 (VBoxClient) crashed in XQueryExtension()
Feb 25 08:12:30 luks systemd-coredump[1479]: Process 1473 (VBoxClient) of user 1000 dumped core.
                                             
Stack trace of thread 1473:
#0  0x00007f99e89cc04f XQueryExtension (libX11.so.6 + 0x3d04f)
#1  0x00007f99e89bf4a7 XInitExtension (libX11.so.6 + 0x304a7)
#2  0x00007f99e890e6d1 XextAddDisplay (libXext.so.6 + 0xe6d1)
#3  0x00007f99e8984a50 XRRFindDisplay.part.0 (libXrandr.so.2 + 0x2a50)
#4  0x00007f99e89851d8 XRRQueryExtension (libXrandr.so.2 + 0x31d8)
#5  0x00000000004090da _ZL3runPP11VBCLSERVICEb (VBoxClient + 0x90da)
#6  0x00000000004076ec main (VBoxClient + 0x76ec)
#7  0x00007f99e871c042 __libc_start_main (libc.so.6 + 0x27042)
#8  0x00000000004078de _start (VBoxClient + 0x78de)

[Konstantin Pelepelin]

I've got a similar crash on VirtualBox 6.1.4 Windows host, VBoxSVGA, LUbuntu 18.04 guest (freshly installed), kernel 5.3 ("hwe"). dmesg log was full of repetitive crash lines regarding VboxClient and libX11. Shared clipboard and guest auto-resize did not work. Re-installed 6.0.18 and re-installed guest additions, everything is working.

[Willie]

Can reproduce in 6.1.4

Reverted to version 6.1.2 to solve this issue for now.

[hansg]

I've just debugged this and it clearly is a bug introduced in some of the changes in 6.1.4, the "VBoxClient --vmsvga-x11" helper process code now has this code:

VirtualBox-6.1.4/src/VBox/Additions/x11/VBoxClient/display-svga-x11.cpp: x11Connect():

pContext->pDisplay = XOpenDisplay(NULL); if (pContext->pDisplay == NULL)

return;

if(!XQueryExtension(pContext->pDisplay, "VMWARE_CTRL",

&pContext->hVMWMajor, &dummy, &dummy))

{

XCloseDisplay(pContext->pDisplay); pContext->pDisplay = NULL;

}

if (!XRRQueryExtension(pContext->pDisplay, &pContext->hRandREventBase, &pCon {

XCloseDisplay(pContext->pDisplay); pContext->pDisplay = NULL;

}

Notice how the code happily continues after closing the display and setting pContext->pDisplay = NULL when the query for the "VMWARE_CTRL" extension fails; and this will fail when using VboxSVGA as virtual VGA adapter which was the default for a long time, as well as when running a Wayland based desktop and recent GNOME3 versions run as Wayland compositor (rather then on top of X11) by default now, so this is impacting a lot of users.

The fix is to add a return statement after all the pContext->pDisplay = NULL; lines in the x11Connect() function.

[hansg]

Patch fixing the crash

[Frank Batschulat (Oracle)]

this has been fixed in trunc already in revision r136295 and needs backporting to the 6.1 branch.

[Frank Batschulat (Oracle)]

Oracle bugID: 30964278

[Frank Batschulat (Oracle)]

The following GA test build for the 6.1 release train contains the fix:

https://www.virtualbox.org/wiki/Testbuilds
https://www.virtualbox.org/download/testcase/VBoxGuestAdditions_6.1.5-136327.iso

[Frank Batschulat (Oracle)]

this has been fixed in public release 6.1.6