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2c41b52901
Currently, printf needs more stack space than what is available with SIGSTKSZ. This commit use the the write system call directly instead. Also use sig_atomic_t for the “pass” variable (for general correctness), and restore signal handlers to their defaults, to avoid masking crashes.
133 lines
3.2 KiB
C
133 lines
3.2 KiB
C
/* Verify longjmp fortify checking does not reject signal stacks.
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Test case mostly written by Paolo Bonzini <pbonzini@redhat.com>. */
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#include <assert.h>
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#include <setjmp.h>
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#include <signal.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <sys/types.h>
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#include <sys/time.h>
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#include <sys/resource.h>
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#include <unistd.h>
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static jmp_buf mainloop;
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static sigset_t mainsigset;
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static volatile sig_atomic_t pass;
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static void
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write_message (const char *message)
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{
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ssize_t unused __attribute__ ((unused));
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for (int i = 0; i < pass; ++i)
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unused = write (STDOUT_FILENO, " ", 1);
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unused = write (STDOUT_FILENO, message, strlen (message));
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}
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static void
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stackoverflow_handler (int sig)
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{
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stack_t altstack;
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/* Sanity check to keep test from looping forever (in case the longjmp
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chk code is slightly broken). */
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pass++;
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assert (pass < 5);
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sigaltstack (NULL, &altstack);
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write_message ("in signal handler\n");
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if (altstack.ss_flags & SS_ONSTACK)
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write_message ("on alternate stack\n");
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siglongjmp (mainloop, pass);
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}
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static volatile int *
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recurse_1 (int n, volatile int *p)
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{
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if (n >= 0)
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*recurse_1 (n + 1, p) += n;
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return p;
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}
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static int
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recurse (int n)
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{
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int sum = 0;
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return *recurse_1 (n, &sum);
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}
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static int
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do_test (void)
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{
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char mystack[SIGSTKSZ];
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stack_t altstack;
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struct sigaction action;
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sigset_t emptyset;
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/* Before starting the endless recursion, try to be friendly to the user's
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machine. On some Linux 2.2.x systems, there is no stack limit for user
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processes at all. We don't want to kill such systems. */
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struct rlimit rl;
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rl.rlim_cur = rl.rlim_max = 0x100000; /* 1 MB */
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setrlimit (RLIMIT_STACK, &rl);
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/* Install the alternate stack. */
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altstack.ss_sp = mystack;
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altstack.ss_size = sizeof (mystack);
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altstack.ss_flags = 0; /* no SS_DISABLE */
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if (sigaltstack (&altstack, NULL) < 0)
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{
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puts ("first sigaltstack failed");
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return 0;
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}
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/* Install the SIGSEGV handler. */
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sigemptyset (&action.sa_mask);
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action.sa_handler = &stackoverflow_handler;
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action.sa_flags = SA_ONSTACK;
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sigaction (SIGSEGV, &action, (struct sigaction *) NULL);
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sigaction (SIGBUS, &action, (struct sigaction *) NULL);
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/* Save the current signal mask. */
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sigemptyset (&emptyset);
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sigprocmask (SIG_BLOCK, &emptyset, &mainsigset);
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/* Provoke two stack overflows in a row. */
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if (sigsetjmp (mainloop, 1) != 0)
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{
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assert (pass != 0);
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printf ("%*sout of signal handler\n", pass, "");
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}
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else
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assert (pass == 0);
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sigaltstack (NULL, &altstack);
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if (altstack.ss_flags & SS_ONSTACK)
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printf ("%*son alternate stack\n", pass, "");
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else
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printf ("%*snot on alternate stack\n", pass, "");
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if (pass < 2)
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{
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recurse (0);
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puts ("recurse call returned");
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return 2;
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}
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altstack.ss_flags |= SS_DISABLE;
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if (sigaltstack (&altstack, NULL) == -1)
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printf ("disabling alternate stack failed\n");
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else
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printf ("disabling alternate stack succeeded \n");
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/* Restore the signal handlers, in case we trigger a crash after the
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tests above. */
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signal (SIGBUS, SIG_DFL);
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signal (SIGSEGV, SIG_DFL);
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return 0;
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}
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#define TEST_FUNCTION do_test ()
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#include "../test-skeleton.c"
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