Date: Sat, 30 Mar 2002 09:38:37 -0800 (PST) From: Gurusamy Sarathy <gsar@ActiveState.com> To: freebsd-gnats-submit@FreeBSD.org Subject: kern/36539: installing a SIGCHLD handler makes libc_r coredump Message-ID: <200203301738.g2UHcbs12872@freefall.freebsd.org>
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>Number: 36539
>Category: kern
>Synopsis: installing a SIGCHLD handler makes libc_r coredump
>Confidential: no
>Severity: critical
>Priority: high
>Responsible: freebsd-bugs
>State: open
>Quarter:
>Keywords:
>Date-Required:
>Class: sw-bug
>Submitter-Id: current-users
>Arrival-Date: Sat Mar 30 09:40:01 PST 2002
>Closed-Date:
>Last-Modified:
>Originator: Gurusamy Sarathy
>Release: 4.2
>Organization:
ActiveState Corp.
>Environment:
FreeBSD clamp 4.2-RELEASE FreeBSD 4.2-RELEASE #0: Mon Nov 20 13:02:55 GMT 2000 jkh@bento.FreeBSD.org:/usr/src/sys/compile/GENERIC i386
>Description:
The test case should be self-explanatory.
% cc -g -o sig sig.c
% ./sig
Fatal error '_pq_remove: Not in priority queue' at line ? in file /usr/src/lib/libc_r/uthread/uthread_priority_queue.c (errno = ?)
Abort (core dumped)
% gdb ./sig ./sig.core
GNU gdb 4.18
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This GDB was configured as "i386-unknown-freebsd"...
Core was generated by `sig'.
Program terminated with signal 6, Abort trap.
Reading symbols from /usr/lib/libc_r.so.4...done.
Reading symbols from /usr/libexec/ld-elf.so.1...done.
#0 0x280a4320 in kill () from /usr/lib/libc_r.so.4
(gdb) bt
#0 0x280a4320 in kill () from /usr/lib/libc_r.so.4
#1 0x280ee6a6 in abort () from /usr/lib/libc_r.so.4
#2 0x280baffd in _thread_exit () from /usr/lib/libc_r.so.4
#3 0x280b440e in _pq_remove () from /usr/lib/libc_r.so.4
#4 0x280b6cb5 in _thread_kern_scheduler () from /usr/lib/libc_r.so.4
#5 0x0 in ?? ()
(gdb) q
>How-To-Repeat:
/*
* Demonstrate crash in libc when a SIGCHLD handler is installed
* either using sigaction() or signal() on FreeBSD 4.2-RELEASE.
*
* This program has different behavior when built with and without
* -pthread. When built with -pthread, it will coredump somewhere
* in libc's uthread_priority_queue.c after running for a few
* seconds.
*
* Build with:
* cc -g -o sig sig.c -pthread
*/
#include <stdio.h>
#include <signal.h>
#include <errno.h>
#include <unistd.h>
#include <sys/syscall.h>
#include <sys/types.h>
#include <sys/wait.h>
void
reaper(int sig)
{
int status;
pid_t pid;
int save_errno = errno;
while ((pid = waitpid(-1, &status, WNOHANG)) > 0)
;
errno = save_errno;
return;
}
int
main(int ac, char **av)
{
struct sigaction sa;
sa.sa_handler = reaper;
sa.sa_flags = 0;
sigemptyset(&sa.sa_mask);
sigaction(SIGCHLD,&sa,NULL);
/*signal(SIGCHLD,reaper);*/ /* this has the same problem */
/*syscall(SYS_sigaction,SIGCHLD,&sa,NULL);*/ /* workaround */
while (1) {
pid_t c = fork();
if (c < 0) {
fprintf(stderr, "fork() failed: %s\n", strerror(errno));
exit(1);
}
if (!c) {
exit(0);
}
usleep(1); /* slow down, don't make too many children */
}
}
>Fix:
None known. See workaround mentioned in the test case.
>Release-Note:
>Audit-Trail:
>Unformatted:
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