Bug 1352124 - segfault when using timer_create with SIGEV_THREAD and a low timer interval
Summary: segfault when using timer_create with SIGEV_THREAD and a low timer interval
Alias: None
Product: Fedora
Classification: Fedora
Component: glibc
Version: 24
Hardware: Unspecified
OS: Unspecified
Target Milestone: ---
Assignee: glibc team
QA Contact: Fedora Extras Quality Assurance
Depends On:
TreeView+ depends on / blocked
Reported: 2016-07-01 16:53 UTC by Cristian Morales Vega
Modified: 2017-07-26 08:46 UTC (History)
9 users (show)

Fixed In Version:
Doc Type: If docs needed, set a value
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Clone Of:
Last Closed: 2017-07-26 08:46:13 UTC
Type: Bug

Attachments (Terms of Use)

System ID Private Priority Status Summary Last Updated
Sourceware 20340 0 None None None 2019-01-11 21:07:47 UTC

Description Cristian Morales Vega 2016-07-01 16:53:28 UTC
Running this program results in a segfault.

#include <signal.h>
#include <time.h>
#include <limits.h>
#include <unistd.h>
#include <stdio.h>

static void sigev_notify(union sigval arg) {}

int main() {
	timer_t timerid;
	static struct sigevent sevp = {
		.sigev_notify = SIGEV_THREAD,
		.sigev_notify_function = sigev_notify

	timer_create(CLOCK_MONOTONIC, &sevp, &timerid);

	static const struct itimerspec new_value = {
		.it_interval = {
			.tv_sec = 0,
			.tv_nsec = 1000
		.it_value = {
			.tv_sec = 0,
			.tv_nsec = 1000

	timer_settime(&timerid, 0, &new_value, NULL);


The problem happens when SIGEV_THREAD is used with a too low timer interval. Seems to be related to the new thread stack allocation, but I didn't check in detail.

Maybe the problem can be reproduced without using timers, just using pthread_create() in a for loop in a pair of threads, but I have not tried.

Comment 1 Carlos O'Donell 2016-07-08 21:01:34 UTC
If you slow down the application even slightly with strace it works. Similarly with gdb when you slow it down to send thread creation events it works.

Filed upstream:

This needs deeper investigation by the community.

Comment 2 Fedora End Of Life 2017-07-25 21:29:43 UTC
This message is a reminder that Fedora 24 is nearing its end of life.
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Comment 3 Cristian Morales Vega 2017-07-26 06:12:17 UTC
I'm actually unable to reproduce this in Fedora 26 (glibc 2.25).

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