Bug 35524 - gdb can't attach on ubuntu 14.04 to get stack trace on crash
Summary: gdb can't attach on ubuntu 14.04 to get stack trace on crash
Alias: None
Product: Runtime
Classification: Mono
Component: General ()
Version: 4.0.0
Hardware: PC Mac OS
: --- trivial
Target Milestone: ---
Assignee: Bugzilla
Depends on:
Reported: 2015-11-04 04:59 UTC by Rolf Bjarne Kvinge [MSFT]
Modified: 2015-11-09 18:08 UTC (History)
3 users (show)

Is this bug a regression?: ---
Last known good build:

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Description Rolf Bjarne Kvinge [MSFT] 2015-11-04 04:59:03 UTC
This is printed:

> Debug info from gdb:
> Could not attach to process.  If your uid matches the uid of the target
> process, check the setting of /proc/sys/kernel/yama/ptrace_scope, or try
> again as the root user.  For more details, see /etc/sysctl.d/10-ptrace.conf
> ptrace: Operation not permitted.
> No threads.

/etc/sysctl.d/10-ptrace.conf says:

> # For applications launching crash handlers that need PTRACE, exceptions can
> # be registered by the debugee by declaring in the segfault handler
> # specifically which process will be using PTRACE on the debugee:
> #   prctl(PR_SET_PTRACER, debugger_pid, 0, 0, 0);

So this would be a suggestion to add a call to prctl inside mono.

$ uname -a
Linux ip-10-178-203-228 3.13.0-48-generic #80-Ubuntu SMP Thu Mar 12 11:16:15 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux

$ lsb_release  -a
No LSB modules are available.
Distributor ID:	Ubuntu
Description:	Ubuntu 14.04.3 LTS
Release:	14.04
Codename:	trusty
Comment 1 Zoltan Varga 2015-11-09 18:08:41 UTC
This was already fixed by 856436879 in master/4.2.