I have a Python program that sometimes crashes due to a "double free or corruption" error. I am trying to figure out where this is happening (possibly in one of the many libraries I am using) so that I can prevent it from crashing. To that end I enabled core dumps, and I now have an Apport .crash file to work with.
Here's where I'm stuck. How do I load the core dump into gdb or something else that will let me see whatever stacktrace information is available?
apport-retrace seems like it would be great, but won't load because there's no package in the .crash file:
ERROR: report file does not contain one of the required fields: CoreDump DistroRelease Package ExecutablePath
I also can't figure out how to load it directly into gdb. I've tried gdb /usr/bin/python <crashfile> on the full .crash file, on just the "CoreDump" portion of the .crash file, and on a base64-decoded version of the "CoreDump" section. Each time I've gotten this error:
<crashfile> is not a core dump: File format not recognized
Is there a way I can either use apport-retrace without needing a package or pull the core dump out of the crash file in a way that gdb can use it?
It turns out it was fairly simple to modify the .crash file to allow apport-retrace to open it. I simply needed to add
Package: python2.7
to the file. For good measure, I also made sure that the "ExecutablePath" was for Python:
ExecutablePath: /usr/bin/python2.7
In my case, the executable path was previously a different file (one specific to my program). I don't know if this step was actually necessary.
After doing this, I could run apport-retrace -g <crashfile> to open it up in gdb and then use bt to extract the stacktrace.