Date: Wed, 25 Oct 2000 02:29:49 -0700 (PDT) From: Bram@vim.org To: freebsd-gnats-submit@FreeBSD.org Subject: bin/22286: siglongjmp does not properly restore the signal stack Message-ID: <20001025092949.2867637B479@hub.freebsd.org>
next in thread | raw e-mail | index | archive | help
>Number: 22286
>Category: bin
>Synopsis: siglongjmp does not properly restore the signal stack
>Confidential: no
>Severity: serious
>Priority: high
>Responsible: freebsd-bugs
>State: open
>Quarter:
>Keywords:
>Date-Required:
>Class: sw-bug
>Submitter-Id: current-users
>Arrival-Date: Wed Oct 25 02:30:01 PDT 2000
>Closed-Date:
>Last-Modified:
>Originator: Bram Moolenaar
>Release: 4.0 release
>Organization:
>Environment:
FreeBSD masaka.moolenaar.net 4.0-RELEASE FreeBSD 4.0-RELEASE #2: Mon Oct 16 18:20:45 CEST 2000 mool@masaka.moolenaar.net:/usr/src/sys/compile/MASAKA i386
>Description:
When using siglongjmp() to jump from a signal handler back to the main code, while the signal function uses the signal stack (defined with sigaltstack()), this works only once. The next time the signal handler is called the program crashes, apparently because the signal stack is not operating. Setting the signal stack again (with sigaltstack()) works around the problem. The same code works fine on other systems that have sigaltstack().
>How-To-Repeat:
Compile and run the program below. Result:
In while
Signal recieved!
In while
Illegal instruction(core dumped)
Now define "WORKAROUND" and do it again. Result:
In while
Signal recieved!
In while
Signal recieved!
In while
Signal recieved!
etc.
#include <signal.h>
#include <stdio.h>
#include <setjmp.h>
#include <stdlib.h>
#include <string.h>
/* #define WORKAROUND */
sigjmp_buf env;
stack_t ss;
struct sigaction sa;
void foo(void)
{
int a[32768];
foo(); /* recursively call ourselves until out of stack space */
}
void sighandler(int sig)
{
siglongjmp(env, 100);
}
main() {
if ((ss.ss_sp = malloc(SIGSTKSZ)) == NULL)
exit(1);
ss.ss_size = SIGSTKSZ;
ss.ss_flags = 0;
if (sigaltstack(&ss,(stack_t *)0) < 0) {
perror("sigaltstack");
exit(1);
}
sa.sa_handler = sighandler;
sa.sa_flags = SA_ONSTACK;
if (sigaction(SIGSEGV, &sa, 0) < 0) {
perror("sigaction");
exit(1);
}
while (1) {
puts("In while");
if (!sigsetjmp(env, 1))
foo();
else
{
puts("Signal recieved!");
#ifdef WORKAROUND
if (sigaltstack(&ss, (stack_t *)0) < 0) {
perror("sigaltstack");
exit(1);
}
#endif
}
}
}
>Fix:
No known solution
>Release-Note:
>Audit-Trail:
>Unformatted:
To Unsubscribe: send mail to majordomo@FreeBSD.org
with "unsubscribe freebsd-bugs" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?20001025092949.2867637B479>