Bug 13293
| Summary: | You can catch SIGKILL and SIGSTOP in 4.0. | ||
|---|---|---|---|
| Product: | Base System | Reporter: | dwmalone <dwmalone> |
| Component: | kern | Assignee: | Martin Cracauer <cracauer> |
| Status: | Closed FIXED | ||
| Severity: | Affects Only Me | CC: | cracauer |
| Priority: | Normal | ||
| Version: | 4.0-CURRENT | ||
| Hardware: | Any | ||
| OS: | Any | ||
Responsible Changed From-To: freebsd-bugs->cracauer Rev 1.57 was martin's baby. State Changed From-To: open->closed The suggested fix has been reviewed and committed in version 1.61 of kern_sig.c. No releases shipped with that bug. Other branches than 4.0-current were not affected. Thanks for the detailed bug report. |
Sigaction is supposed to check if you change the handler of SIGKILL or SIGSTOP to anything but SIG_DFL. In revision 1.57 one instance too many of sa->sa_handler got replaced by ps->ps_sigact[signum]. Resultingly it checks if the current handler is SIG_DFL instead of the new handler being SIG_DFL. This means you can create un-killable un-stoppable processes. Fix: --- kern_sig.c 1999/08/16 18:13:38 1.60 +++ kern_sig.c 1999/08/21 16:06:30 @@ -155,11 +155,11 @@ if (uap->nsa) { if ((error = copyin((caddr_t)uap->nsa, (caddr_t)sa, sizeof (vec)))) return (error); if ((signum == SIGKILL || signum == SIGSTOP) && - ps->ps_sigact[signum] != SIG_DFL) + sa->sa_handler != SIG_DFL) return (EINVAL); setsigvec(p, signum, sa); } return (0); } How-To-Repeat: The following program is unkillable. #include <stdio.h> #include <sys/types.h> #include <signal.h> void sighand(int sig) { printf("Caught signal %d\n",sig); } int main(int argc,char **argv) { int i; for( i = 0 ; i < 32 ; i++ ) signal(i,sighand); while(1); exit(0); }