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86 lines
2.4 KiB

Based on the following commits:
commit 2c41b52901331f5c761015af786a3976e225d779
Author: Florian Weimer <fweimer@redhat.com>
Date: Mon Jun 13 13:08:39 2016 +0200
debug/tst-longjmp_chk2: Make signal handler more conservative [BZ #20248]
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.
commit 5896c8bdd9f73cdc816a96e107ca1f7a6bc6921e
Author: Mike Frysinger <vapier@gentoo.org>
Date: Sun Dec 29 16:30:35 2013 -0500
tst-longjmp_chk2: add comments/sanity check
If the longjmp checking code is slightly broken, this code can loop
forever which isn't too helpful. Add a sanity check to keep that
from happening.
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Index: b/debug/tst-longjmp_chk2.c
===================================================================
--- a/debug/tst-longjmp_chk2.c
+++ b/debug/tst-longjmp_chk2.c
@@ -4,27 +4,36 @@
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
+#include <string.h>
#include <sys/types.h>
#include <sys/time.h>
#include <sys/resource.h>
+#include <unistd.h>
static jmp_buf mainloop;
static sigset_t mainsigset;
-static int pass;
+static volatile sig_atomic_t pass;
+static void
+write_message (const char *message)
+{
+ ssize_t unused __attribute__ ((unused));
+ for (int i = 0; i < pass; ++i)
+ unused = write (STDOUT_FILENO, " ", 1);
+ unused = write (STDOUT_FILENO, message, strlen (message));
+}
static void
stackoverflow_handler (int sig)
{
stack_t altstack;
pass++;
+ assert (pass < 5);
sigaltstack (NULL, &altstack);
- /* Using printf is not really kosher in signal handlers but we know
- it will work. */
- printf ("%*sin signal handler\n", pass, "");
+ write_message ("in signal handler\n");
if (altstack.ss_flags & SS_ONSTACK)
- printf ("%*son alternate stack\n", pass, "");
+ write_message ("on alternate stack\n");
siglongjmp (mainloop, pass);
}
@@ -107,6 +116,11 @@ do_test (void)
else
printf ("disabling alternate stack succeeded \n");
+ /* Restore the signal handlers, in case we trigger a crash after the
+ tests above. */
+ signal (SIGBUS, SIG_DFL);
+ signal (SIGSEGV, SIG_DFL);
+
return 0;
}