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Bug #425

closed
MB DG

lttng-sessiond gets a segmentation fault

Bug #425: lttng-sessiond gets a segmentation fault

Added by Mathieu Bain about 13 years ago. Updated about 13 years ago.

Status:
Resolved
Priority:
Normal
Assignee:
David Goulet
Target version:
LTTng - 2.1 stable
Start date:
01/18/2013
Due date:
% Done:

0%

Estimated time:

Description

Situation:
A session is running and just before destroying the session, we launch a bunch of instrumented application.
This made lttng-sessiond do a core dump.

By analyzing the core file, the core dump happened in create_ust_channel.c at line 783
I attached the small analyze that I ran with gdb on the core file.

The version of Lttng used is 1.2.0 with:
lttng-tools: 2.1.1
lttng-ust: 2.1.0
userspace-rcu: 0.7.5

Files

logs.txt (16.6 KB) logs.txt Mathieu Bain, 01/18/2013 04:07 PM

DG Updated by David Goulet about 13 years ago Actions
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 #1

  • Status changed from New to Confirmed
  • Assignee set to David Goulet
  • Target version set to 2.1 stable

DG Updated by David Goulet about 13 years ago Actions
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 #2

If you can reproduce that with no optimization (gcc -O0), it would be great since the ret value here is quite important. It seems that a ustctl_create_channel call returned a positive value but actually failed to populate the obj.

Furthermore, no optimization will ensure that the segfault is really at that place with more information as well.

Thanks!

DG Updated by David Goulet about 13 years ago Actions
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 #3

This might be fixed with the latest commit of lttng-ust.

(stable-2.1) c7b9470b6849bc42d0c3a835b917e764e8c13fc9

There was a code path that could have sent a positive value on error.

Thanks

DG Updated by David Goulet about 13 years ago Actions
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 #4

  • Status changed from Confirmed to Feedback

MB Updated by Mathieu Bain about 13 years ago Actions
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 #5

Hi David,

I tested the patch and up to now i don't see the issue any more.
If this shows up sometime later, i will raise a new bug

Thanks

DG Updated by David Goulet about 13 years ago Actions
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 #6

  • Status changed from Feedback to Resolved

Ok. Fair enough, I'll close this one since we can't do much for now.

Thanks!

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