X2Go Bug report logs - #900
Gedit, gnome-terminal and others crash in rootless mode

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Message #5 received at submit@bugs.x2go.org (full text, mbox, reply):

From: Camilo Alejandro Arboleda <camilo@ieee.org>

To: submit@bugs.x2go.org

Subject: Gedit, gnome-terminal and others crash in rootless mode

Date: Thu, 02 Jul 2015 08:21:22 +0200

[Message part 1 (text/plain, inline)]

Package: libnx-X11

Version: 2.3.5

Setup:

 1. x2goserver in a debian testing machine.
 2. x2goclient in a windows machine.
 3. Create a session with a virtual desktop.
 4. Run gedit in the session created in 3.
 5. Create a session in windows launching only xterm.
 6. Run gedit from the console created in 5.
 7. Create a session in windows launching only gedit.

Results:

 1. Steps from Setup 3, 4 and 5 work fine.
 2. Steps from Setup 6 and 7 crash (close the session).


A quick look in dmesg shows that *libNX_X11.so.6.2* caused a SEGFAULT.

Running x2goagent with a debugger gives the following backtrace:

*(gdb) backtrace*
#0  _XData32 (dpy=dpy@entry=0xf591b0, data=data@entry=0x163c2c4,
len=len@entry=18652) at XlibInt.c:3775
#1  0x00007f759e34dce1 in XChangeProperty (dpy=0xf591b0, w=<optimized
out>, property=<optimized out>, type=6, format=<optimized out>,
mode=<optimized out>,
    data=0x163c2c4
"\377\377\377\377\354\356\356\377\377\377\377\377\354\356\356\377\377\377\377\377\354\356\356\377\377\377\377\377\357\360\360\377\377\377\377\377\364\365\365\377\377\377\377\377\307\312\311\375\377\377\377\377\t\t\t\035",
nelements=4663) at ChProp.c:85
#2  0x00000000004b1e37 in nxagentExportProperty (pWin=0x20,
property=*4663*, type=23315140, format=4669, mode=32, nUnits=*4663*,
value=0x15fc2e0) at Rootless.c:763
#3  0x000000000042222a in ProcChangeProperty (client=0xf591b0) at
X/NXproperty.c:331
#4  0x000000000042eea2 in Dispatch () at X/NXdispatch.c:748

Looking at the highlighted values, it seems that gedit is sending a
malformed ChangeProperty request, and rootless is failing to process it.

Specifically the segment between lines 735-780, tries to set a property
that is bigger than the maximum size required, but because it's a
malformed request it ends up writing in memory outside the boundaries of
the output buffer.

Alternatives:

 1. Ensure that nxagentExportProperty never writes beyond the boundaries
    of the output buffer.
 2. Resize the output buffer to match the required size
    (ProcChangeProperty seems to do something similar).
 3. Ignore big requests (see attached patch).


-- 

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[fail_on_big_requests.patch (text/x-patch, attachment)]

🔗 View this message in rfc822 format

From: Mike Gabriel <mike.gabriel@das-netzwerkteam.de>

To: Camilo Alejandro Arboleda <camilo@ieee.org>, 900@bugs.x2go.org

Subject: Bug#900: [X2Go-Dev] Bug#900: Gedit, gnome-terminal and others crash in rootless mode

Date: Tue, 23 Feb 2016 14:29:08 +0000

[Message part 1 (text/plain, inline)]

Control: tags -1 patch
Control: forwarded -1 https://github.com/ArcticaProject/nx-libs/issues/82

Hi Camilo,

On  Do 02 Jul 2015 08:21:22 CEST, Camilo Alejandro Arboleda wrote:

Your bug report has just been moved [1] to the new upstream location  
of nx-libs on Github.

> Looking at the highlighted values, it seems that gedit is sending a
> malformed ChangeProperty request, and rootless is failing to process it.

Is it really a malformed request or a problem with broken BIG-REQUESTS  
support [2] in libXcomp3 (aka nxcomp)?

> Specifically the segment between lines 735-780, tries to set a property
> that is bigger than the maximum size required, but because it's a
> malformed request it ends up writing in memory outside the boundaries of
> the output buffer.
>
> Alternatives:
>
>  1. Ensure that nxagentExportProperty never writes beyond the boundaries
>     of the output buffer.
>  2. Resize the output buffer to match the required size
>     (ProcChangeProperty seems to do something similar).
>  3. Ignore big requests (see attached patch).

Is option 3. really the optimal approach? It feels like option 2.  
would be the way to go here...

Please continue, if possible for you, this discussion on Github.

Mike

[1] https://github.com/ArcticaProject/nx-libs/issues/82
[2] https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=766299
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Message #26 received at 900-submit@bugs.x2go.org (full text, mbox, reply):

From: "FedEx International Next Flight" <allan.haas@signatureluxuryauctions.com>

To: 900-submit@bugs.x2go.org

Subject: Problem with parcel shipping, ID:0000353890

Date: Tue, 18 Oct 2016 11:28:03 -0500

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Dear Customer,

We could not deliver your item.
Delivery Label is attached to this email.

Yours trully,
Allan Haas,
Sr. Station Manager.

[0000353890.zip (application/zip, attachment)]

Message #31 received at 900@bugs.x2go.org (full text, mbox, reply):

From: "FedEx International Next Flight" <danny.durham@egescapes.com>

To: 900@bugs.x2go.org

Subject: Problem with parcel shipping, ID:000715375

Date: Mon, 24 Oct 2016 06:37:09 +0000

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Dear Customer,

Your parcel has arrived at October 22. Courier was unable to deliver the parcel to you.
You can review complete details of your order in the find attached.

Warm regards,
Danny Durham,
Station Manager.

[000715375.zip (application/zip, attachment)]

Message #36 received at 900@bugs.x2go.org (full text, mbox, reply):

From: "FedEx 2Day A.M." <larry.springer@doctorprior.com>

To: 900@bugs.x2go.org

Subject: Problem with parcel shipping, ID:000224558

Date: Thu, 3 Nov 2016 07:09:16 +0000

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Dear Customer,

Your parcel has arrived at November 01. Courier was unable to deliver the parcel to you.
You can review complete details of your order in the find attached.

Yours faithfully,
Larry Springer,
Sr. Support Agent.

[FedEx_000224558.zip (application/zip, attachment)]

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