marco crashed with SIGSEGV in INT_cairo_region_num_rectangles()

[Martin Wimpress ]

I was dragging windows to the edge of the screen to snap them to half the screen shortly before this crash was captured.

ProblemType: Crash
DistroRelease: Ubuntu 20.04
Package: marco 1.24.0-0ubuntu1
ProcVersionSignature: Ubuntu 5.4.0-14.17-generic 5.4.18
Uname: Linux 5.4.0-14-generic x86_64
ApportVersion: 2.20.11-0ubuntu16
Architecture: amd64
CrashCounter: 1
CurrentDesktop: MATE
Date: Sat Feb 15 00:24:19 2020
ExecutablePath: /usr/bin/marco
InstallationDate: Installed on 2020-02-13 (1 days ago)
InstallationMedia: Ubuntu-MATE 20.04 LTS "Focal Fossa" - Alpha amd64 (20200213)
ProcCmdline: marco
ProcEnviron:
 LANGUAGE=en_GB:en
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_GB.UTF-8
 SHELL=/bin/bash
SegvAnalysis:
 Segfault happened at: 0x7f392cf669d4 <cairo_region_num_rectangles+4>: mov 0x4(%rdi),%eax
 PC (0x7f392cf669d4) ok
 source "0x4(%rdi)" (0x000000f5) not located in a known VMA region (needed readable region)!
 destination "%eax" ok
SegvReason: reading NULL VMA
Signal: 11
SourcePackage: marco
StacktraceTop:
 cairo_region_num_rectangles () from /lib/x86_64-linux-gnu/libcairo.so.2
 ?? () from /lib/x86_64-linux-gnu/libmarco-private.so.2
 ?? () from /lib/x86_64-linux-gnu/libmarco-private.so.2
 ?? () from /lib/x86_64-linux-gnu/libmarco-private.so.2
 ?? () from /lib/x86_64-linux-gnu/libmarco-private.so.2
Title: marco crashed with SIGSEGV in cairo_region_num_rectangles()
UpgradeStatus: No upgrade log present (probably fresh install)
UserGroups: adm cdrom dip libvirt lpadmin lxd plugdev sambashare sudo
separator:

[Apport retracing service (apport)]

StacktraceTop:
 INT_cairo_region_num_rectangles (region=region@entry=0xf1) at ../../../../src/cairo-region.c:451
 cairo_region_to_xserver_region (xdisplay=xdisplay@entry=0x5607cfdef640, region=0xf1) at compositor/compositor-xrender.c:607
 border_size (cw=0x5607d0302e20) at compositor/compositor-xrender.c:1157
 paint_windows (region=10566623, root_pixmap=<optimized out>, root_buffer=<optimized out>, windows=<optimized out>, screen=0x5607cffdfd00) at compositor/compositor-xrender.c:1420
 paint_all (screen=screen@entry=0x5607cffdfd00, region=region@entry=10566623, b=<optimized out>) at compositor/compositor-xrender.c:1593

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Launchpad Janitor (janitor)]

This bug was fixed in the package marco - 1.24.0-1ubuntu1

---------------
marco (1.24.0-1ubuntu1) focal; urgency=medium

  * debian/patches:
    + Add 0001_fix-segfaults.patch. Fix calculation of borders to
      prevent segfaults. (LP: #1863431, #1863392)

 -- Martin Wimpress <email address hidden> Mon, 23 Mar 2020 23:18:18 +0000

[Jared Punzel (jpunzel)]

This appears to have not been fixed in 1.24.0-1ubuntu1 on the latest 20.04. It happens at occasional times when I close a window. There are some similar recent reports on the github page:
https://github.com/mate-desktop/marco/issues/617
https://github.com/mate-desktop/marco/issues/661

Here's a backtrace from the core dump:

Core was generated by `marco'.
Program terminated with signal SIGSEGV, Segmentation fault.
#0 0x00007f05e10699d4 in cairo_region_num_rectangles () from /usr/lib/x86_64-linux-gnu/libcairo.so.2
[Current thread is 1 (Thread 0x7f05dfb5aa80 (LWP 454768))]
(gdb) bt
#0 0x00007f05e10699d4 in cairo_region_num_rectangles () at /usr/lib/x86_64-linux-gnu/libcairo.so.2
#1 0x00007f05e1d3541e in () at /usr/lib/x86_64-linux-gnu/libmarco-private.so.2
#2 0x00007f05e1d37944 in () at /usr/lib/x86_64-linux-gnu/libmarco-private.so.2
#3 0x00007f05e1d38b1e in () at /usr/lib/x86_64-linux-gnu/libmarco-private.so.2
#4 0x00007f05e1d3a0c9 in () at /usr/lib/x86_64-linux-gnu/libmarco-private.so.2
#5 0x00007f05e1d42b06 in () at /usr/lib/x86_64-linux-gnu/libmarco-private.so.2
#6 0x00007f05e1d8cbb9 in () at /usr/lib/x86_64-linux-gnu/libmarco-private.so.2
#7 0x00007f05e122405f in () at /usr/lib/x86_64-linux-gnu/libgdk-3.so.0
#8 0x00007f05e122444a in () at /usr/lib/x86_64-linux-gnu/libgdk-3.so.0
#9 0x00007f05e11ec0f4 in gdk_display_get_event () at /usr/lib/x86_64-linux-gnu/libgdk-3.so.0
#10 0x00007f05e12240f6 in () at /usr/lib/x86_64-linux-gnu/libgdk-3.so.0
#11 0x00007f05e1e0af9d in g_main_context_dispatch () at /usr/lib/x86_64-linux-gnu/libglib-2.0.so.0
#12 0x00007f05e1e0b220 in () at /usr/lib/x86_64-linux-gnu/libglib-2.0.so.0
#13 0x00007f05e1e0b513 in g_main_loop_run () at /usr/lib/x86_64-linux-gnu/libglib-2.0.so.0
#14 0x0000561e8df74233 in main ()

[Miguel Ángel (zurashu)]

I have the same exact same backtrace on my core dumps as Jared Punzel. For me, it happens each time VSCode is launched or reloaded.

[Bert Driehuis (driehuis)]

I also still get the occasional Marco crash with a backtrace pointing to cairo_region_num_rectangles. If I can do something to assist tracking this down I'm all ears. I can confirm I'm running Marco built off sources that contain the fix, i.e. marco 1.24.0-1ubuntu1. My stacktrace looks identical to the one in comment #8. The SegvAnalysis looks the same as in the original report.

I cannot tell from my backtrace what the offending code path is: apply_cairo_region_to_window(), meta_frames_draw() or cairo_region_to_xserver_region(). I have installed dbgsyms for marco and libcairo2 and will report back if I can get a handle on the issue.