Re: [PATCH 0/4] coredump: core dump masking support v3

From: Markus Gutschke
Date: Fri Feb 23 2007 - 22:33:18 EST

Kawai, Hidehiro wrote:
This patch series is version 3 of the core dump masking feature,
which provides a per-process flag not to dump anonymous shared
memory segments.

I just wanted to remind you that you need to be careful about dumping the [vdso] segment no matter whether you omit other segments. I didn't actually try running your patches, and if the kernel doesn't actually consider this segment anonymous and shared, things might already work fine as is.

In any case, you can check with "readelf -a", if the [vdso] segment is there. And you will find that if you forget to dump it, "gdb" can no longer give you stack traces on call chains that involve signal handlers.

As an alternative to your kernel patch, you could achieve the same goal in user space, by linking my coredumper into your binaries and setting up appropriate signal handlers. An equivalent patch for selectively omitting memory regions would be trivial to add. While this does give you more flexibility, it of course has the drawback of requiring you to change your applications, so there still is some benefit in a kernelspace solution.

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