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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.
This commit is contained in:
Florian Weimer 2016-06-13 13:08:39 +02:00
parent f5c77f78ec
commit 2c41b52901
2 changed files with 27 additions and 5 deletions
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9
ChangeLog
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@ -1,3 +1,12 @@
2016-06-13 Florian Weimer <fweimer@redhat.com>
[BZ #20248]
* debug/tst-longjmp_chk2.c (pass): Use volatile sig_atomic_t.
(write_message): New function.
(stackoverflow_handler): Call it instead of printf, to avoid
excessive stack usage by printf.
(do_test): Restore SIGSEGV, SIGBUS default handlers.
2016-06-13 Adhemerval Zanella <adhemerval.zanella@linaro.org>
* nptl/pthread_mutex_init.c [__ASSUME_FUTEX_LOCK_PI]

23
debug/tst-longjmp_chk2.c
View File

@ -6,15 +6,25 @@
#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)
@ -25,11 +35,9 @@ stackoverflow_handler (int sig)
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);
}
@ -112,6 +120,11 @@ 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;
}