$ uname -a
Linux Longi1 2.4.21-4.EL #1 SMP Fri Oct 3 17:29:39 EDT 2003 ia64 ia64 ia64 GNU/Linux
$ gcc -o sig -g ./sig.c
$ cat sig.c

#include <stdio.h>
#include <signal.h>
void handle(int sig)
{
    int *pt = NULL;
    printf("handled\n");
    *pt = 10;
}
void func1()
{
   signal(SIGUSR1, handle);
   raise(SIGUSR1);
}
func2()
{
func1();
}
main()
{
func2();
}

$ ./sig
handled
Segmentation fault (core dumped)
$ gdb sig ./core.21142
GNU gdb Red Hat Linux (5.3.90-0.20030710.40rh)
Copyright 2003 Free Software Foundation, Inc.
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There is absolutely no warranty for GDB.  Type "show warranty" for details.
This GDB was configured as "ia64-redhat-linux-gnu"...Using host libthread_db library "/lib/tls/libthread_db.so.1".

Core was generated by `./sig'.
Program terminated with signal 11, Segmentation fault.
Reading symbols from /lib/tls/libc.so.6.1...done.
Loaded symbols for /lib/tls/libc.so.6.1
Reading symbols from /lib/ld-linux-ia64.so.2...done.
Loaded symbols for /lib/ld-linux-ia64.so.2
#0  handle (sig=10) at sig.c:7
7	    *pt = 10;
(gdb) where
#0  handle (sig=10) at sig.c:7
#1  <signal handler called>
#2  handle (sig=Cannot access memory at address 0xfffffffffffffff0
) at sig.c:6
Cannot access memory at address 0xffffffffffffffe8
(gdb) quit