minix/test/test62.c
David van Moolenbroek 0a8a2ecfb5 Kernel: pass FPU restore exception to user process
Previously, user processes could cause a kernel panic upon FPU state
restore, by passing bogus FPU state to the kernel (through e.g.
sigreturn). With this patch, the process is now sent a SIGFPE signal
instead.
2012-03-05 22:32:14 +01:00

72 lines
1.3 KiB
C

/* FPU state corruption test. This used to be able to crash the kernel. */
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <signal.h>
#include <sys/wait.h>
#include <machine/fpu.h>
#define MAX_ERROR 1
#include "common.c"
double state = 2.0;
static int count;
static void use_fpu(int n)
{
state += (double) n * 0.5;
}
static void crashed(int sig)
{
exit(EXIT_SUCCESS);
}
static void handler(int sig, int code, struct sigcontext *sc)
{
memset(&sc->sc_fpu_state, count, sizeof(sc->sc_fpu_state));
}
int main(void)
{
int status;
start(62);
subtest = 0;
signal(SIGUSR1, (void (*)(int)) handler);
/* Initialize the FPU state. This state is inherited, too. */
use_fpu(-1);
for (count = 0; count <= 255; count++) {
switch (fork()) {
case -1:
e(1);
break;
case 0:
signal(SIGFPE, crashed);
/* Load bad state into the kernel. */
if (kill(getpid(), SIGUSR1)) e(2);
/* Let the kernel restore the state. */
use_fpu(count);
exit(EXIT_SUCCESS);
default:
/* We cannot tell exactly whether what happened is correct or
* not -- certainly not in a platform-independent way. However,
* if the whole system keeps running, that's good enough.
*/
(void) wait(&status);
}
}
if (state <= 1.4 || state >= 1.6) e(3);
quit();
}