apport computes incorrect core dump size limit

Bug #1346497 reported by Mark Plotnick on 2014-07-21
This bug affects 1 person
Affects Status Importance Assigned to Milestone
apport (Ubuntu)
Martin Pitt

Bug Description

On Ubuntu 14.04, calling the shell's "ulimit -c 20" command sets a ULIMIT_CORE in the kernel of 20480 bytes, as expected, verified by looking at /proc/$$/limits. (This is just an example; I'd likely not use a value that low.) The contents of /proc/sys/kernel/core_pattern is
    |/usr/share/apport/apport %p %s %c %P

When a process gets a memory fault, a core file much larger than 20480 bytes can be created; apport multiplies its third argument, 20480, by 1024, giving a limit of 20MB.

Test program:

#include <sys/time.h>
#include <sys/resource.h>
#include <stdlib.h>
#include <stdio.h>

 struct rlimit r;

 getrlimit(RLIMIT_CORE, &r);
 printf("%ld %ld\n", (long) r.rlim_cur, (long)r.rlim_max);

This produces a core dump of around 1.2MB.
Excerpts from /var/log/apport.log for the test program :

ERROR: apport (pid 4574) Sun Jul 20 21:37:38 2014: called for pid 4573, signal 6, core limit 204800
ERROR: apport (pid 4574) Sun Jul 20 21:37:38 2014: executable: /home/mp/ab (command line "./ab")
ERROR: apport (pid 4574) Sun Jul 20 21:37:38 2014: executable does not belong to a package, ignoring
ERROR: apport (pid 4574) Sun Jul 20 21:37:38 2014: writing core dump to /home/mp/core (limit: 209715200)

Related branches

description: updated
Martin Pitt (pitti) wrote :

Fixed in trunk r2844.

affects: apport → apport (Ubuntu)
Changed in apport (Ubuntu):
assignee: nobody → Martin Pitt (pitti)
status: New → Fix Committed
Launchpad Janitor (janitor) wrote :

This bug was fixed in the package apport - 2.14.7-0ubuntu1

apport (2.14.7-0ubuntu1) utopic; urgency=medium

  * New upstream release:
    - Fix interpretation of core dump ulimits: they are in bytes, not KiB.
      (LP: #1346497)
    - apport-retrace: Don't require specifying an operation; default to
      updating the given .crash file. (LP: #1361242)
    - Write report even on UnreportableReasons, so that whoopsie can still
      upload them. (LP: #1360417)
    - apt/dpkg install_packages(): Write a "packages.txt" into sandbox root
      directory to keep track of installed packages and their versions.
      Prerequisite for LP #1352591.
    - apt/dpkg install_packages(): Avoid re-downloading/installing packages
      which are already installed into a permanent sandbox. Prerequisite for
      LP #1352591.
    -, make_sandbox(): Drop check for already existing files
      when dynamically resolving libraries and ExecutablePaths; with that,
      these packages would never get updated in a permanent sandbox. The new
      version tracking from above now takes care of that. (LP: #1352591)
    - Fix report.test_add_proc_info test to stop assuming that pid 1 is named
      "init", as one can specify a different one on the kernel command line.
    -, add_gdb_info(): Check for truncated core dumps, and set
      UnreportableReason and raise an IOError on them. Handle this in
      apport-retrace and whoopsie-upload-all to fail properly instead of
      silently producing broken Stacktraces. (LP: #1354571)
 -- Martin Pitt <email address hidden> Fri, 29 Aug 2014 12:38:54 +0200

Changed in apport (Ubuntu):
status: Fix Committed → Fix Released
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