Commit bdf6c8b8 authored by Chang S. Bae's avatar Chang S. Bae Committed by Borislav Petkov
Browse files

selftest/sigaltstack: Use the AT_MINSIGSTKSZ aux vector if available 



The SIGSTKSZ constant may not represent enough stack size in some
architectures as the hardware state size grows.

Use getauxval(AT_MINSIGSTKSZ) to increase the stack size.

Signed-off-by: default avatarChang S. Bae <chang.seok.bae@intel.com>
Signed-off-by: default avatarBorislav Petkov <bp@suse.de>
Reviewed-by: default avatarLen Brown <len.brown@intel.com>
Acked-by: default avatarThomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20210518200320.17239-5-chang.seok.bae@intel.com
parent 1c33bb05

tools/testing/selftests/sigaltstack/sas.c

+15 −5
Original line number Diff line number Diff line
@@ -17,6 +17,7 @@ 
#include <string.h>

#include <assert.h>

#include <errno.h>

#include <sys/auxv.h>



#include "../kselftest.h"
@@ -24,6 +25,11 @@ 
#define SS_AUTODISARM  (1U << 31)

#endif



#ifndef AT_MINSIGSTKSZ

#define AT_MINSIGSTKSZ	51

#endif



static unsigned int stack_size;

static void *sstack, *ustack;

static ucontext_t uc, sc;

static const char *msg = "[OK]\tStack preserved";
@@ -47,7 +53,7 @@ void my_usr1(int sig, siginfo_t *si, void *u) 
#endif



	if (sp < (unsigned long)sstack ||

			sp >= (unsigned long)sstack + SIGSTKSZ) {

			sp >= (unsigned long)sstack + stack_size) {

		ksft_exit_fail_msg("SP is not on sigaltstack\n");

	}

	/* put some data on stack. other sighandler will try to overwrite it */
@@ -108,6 +114,10 @@ int main(void) 
	stack_t stk;

	int err;



	/* Make sure more than the required minimum. */

	stack_size = getauxval(AT_MINSIGSTKSZ) + SIGSTKSZ;

	ksft_print_msg("[NOTE]\tthe stack size is %lu\n", stack_size);



	ksft_print_header();

	ksft_set_plan(3);
@@ -117,7 +127,7 @@ int main(void) 
	sigaction(SIGUSR1, &act, NULL);

	act.sa_sigaction = my_usr2;

	sigaction(SIGUSR2, &act, NULL);

	sstack = mmap(NULL, SIGSTKSZ, PROT_READ | PROT_WRITE,

	sstack = mmap(NULL, stack_size, PROT_READ | PROT_WRITE,

		      MAP_PRIVATE | MAP_ANONYMOUS | MAP_STACK, -1, 0);

	if (sstack == MAP_FAILED) {

		ksft_exit_fail_msg("mmap() - %s\n", strerror(errno));
@@ -139,7 +149,7 @@ int main(void) 
	}



	stk.ss_sp = sstack;

	stk.ss_size = SIGSTKSZ;

	stk.ss_size = stack_size;

	stk.ss_flags = SS_ONSTACK | SS_AUTODISARM;

	err = sigaltstack(&stk, NULL);

	if (err) {
@@ -161,7 +171,7 @@ int main(void) 
		}

	}



	ustack = mmap(NULL, SIGSTKSZ, PROT_READ | PROT_WRITE,

	ustack = mmap(NULL, stack_size, PROT_READ | PROT_WRITE,

		      MAP_PRIVATE | MAP_ANONYMOUS | MAP_STACK, -1, 0);

	if (ustack == MAP_FAILED) {

		ksft_exit_fail_msg("mmap() - %s\n", strerror(errno));
@@ -170,7 +180,7 @@ int main(void) 
	getcontext(&uc);

	uc.uc_link = NULL;

	uc.uc_stack.ss_sp = ustack;

	uc.uc_stack.ss_size = SIGSTKSZ;

	uc.uc_stack.ss_size = stack_size;

	makecontext(&uc, switch_fn, 0);

	raise(SIGUSR1);