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Commit 19fd2868 authored by Stas Sergeev's avatar Stas Sergeev Committed by Ingo Molnar
Browse files

selftests/sigaltstack: Add new testcase for sigaltstack(SS_ONSTACK|SS_AUTODISARM) 



This patch adds the test case for SS_AUTODISARM flag.
The test-case tries to set SS_AUTODISARM flag and checks if
the nested signal corrupts the stack after swapcontext().

Signed-off-by: default avatarStas Sergeev <stsp@list.ru>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Shuah Khan <shuahkh@osg.samsung.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-api@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/1460665206-13646-5-git-send-email-stsp@list.ru


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 2a742138

tools/testing/selftests/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -19,6 +19,7 @@ TARGETS += powerpc 
TARGETS += pstore

TARGETS += ptrace

TARGETS += seccomp

TARGETS += sigaltstack

TARGETS += size

TARGETS += static_keys

TARGETS += sysctl

tools/testing/selftests/sigaltstack/Makefile

0 → 100644
+8 −0
Original line number Diff line number Diff line 
CFLAGS = -Wall

BINARIES = sas

all: $(BINARIES)



include ../lib.mk



clean:

	rm -rf $(BINARIES)

tools/testing/selftests/sigaltstack/sas.c

0 → 100644
+156 −0
Original line number Diff line number Diff line 
/*

 * Stas Sergeev <stsp@users.sourceforge.net>

 *

 * test sigaltstack(SS_ONSTACK | SS_AUTODISARM)

 * If that succeeds, then swapcontext() can be used inside sighandler safely.

 *

 */



#define _GNU_SOURCE

#include <signal.h>

#include <stdio.h>

#include <stdlib.h>

#include <sys/mman.h>

#include <ucontext.h>

#include <alloca.h>

#include <string.h>

#include <assert.h>



#ifndef SS_AUTODISARM

#define SS_AUTODISARM  (1 << 4)

#endif



static void *sstack, *ustack;

static ucontext_t uc, sc;

static const char *msg = "[OK]\tStack preserved";

static const char *msg2 = "[FAIL]\tStack corrupted";

struct stk_data {

	char msg[128];

	int flag;

};



void my_usr1(int sig, siginfo_t *si, void *u)

{

	char *aa;

	int err;

	stack_t stk;

	struct stk_data *p;



	register unsigned long sp asm("sp");



	if (sp < (unsigned long)sstack ||

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

		printf("[FAIL]\tSP is not on sigaltstack\n");

		exit(EXIT_FAILURE);

	}

	/* put some data on stack. other sighandler will try to overwrite it */

	aa = alloca(1024);

	assert(aa);

	p = (struct stk_data *)(aa + 512);

	strcpy(p->msg, msg);

	p->flag = 1;

	printf("[RUN]\tsignal USR1\n");

	err = sigaltstack(NULL, &stk);

	if (err) {

		perror("[FAIL]\tsigaltstack()");

		exit(EXIT_FAILURE);

	}

	if (stk.ss_flags != SS_DISABLE)

		printf("[FAIL]\tss_flags=%i, should be SS_DISABLE\n",

				stk.ss_flags);

	else

		printf("[OK]\tsigaltstack is disabled in sighandler\n");

	swapcontext(&sc, &uc);

	printf("%s\n", p->msg);

	if (!p->flag) {

		printf("[RUN]\tAborting\n");

		exit(EXIT_FAILURE);

	}

}



void my_usr2(int sig, siginfo_t *si, void *u)

{

	char *aa;

	struct stk_data *p;



	printf("[RUN]\tsignal USR2\n");

	aa = alloca(1024);

	/* dont run valgrind on this */

	/* try to find the data stored by previous sighandler */

	p = memmem(aa, 1024, msg, strlen(msg));

	if (p) {

		printf("[FAIL]\tsigaltstack re-used\n");

		/* corrupt the data */

		strcpy(p->msg, msg2);

		/* tell other sighandler that his data is corrupted */

		p->flag = 0;

	}

}



static void switch_fn(void)

{

	printf("[RUN]\tswitched to user ctx\n");

	raise(SIGUSR2);

	setcontext(&sc);

}



int main(void)

{

	struct sigaction act;

	stack_t stk;

	int err;



	sigemptyset(&act.sa_mask);

	act.sa_flags = SA_ONSTACK | SA_SIGINFO;

	act.sa_sigaction = my_usr1;

	sigaction(SIGUSR1, &act, NULL);

	act.sa_sigaction = my_usr2;

	sigaction(SIGUSR2, &act, NULL);

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

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

	if (sstack == MAP_FAILED) {

		perror("mmap()");

		return EXIT_FAILURE;

	}

	stk.ss_sp = sstack;

	stk.ss_size = SIGSTKSZ;

	stk.ss_flags = SS_ONSTACK | SS_AUTODISARM;

	err = sigaltstack(&stk, NULL);

	if (err) {

		perror("[FAIL]\tsigaltstack(SS_ONSTACK | SS_AUTODISARM)");

		stk.ss_flags = SS_ONSTACK;

	}

	err = sigaltstack(&stk, NULL);

	if (err) {

		perror("[FAIL]\tsigaltstack(SS_ONSTACK)");

		return EXIT_FAILURE;

	}



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

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

	if (ustack == MAP_FAILED) {

		perror("mmap()");

		return EXIT_FAILURE;

	}

	getcontext(&uc);

	uc.uc_link = NULL;

	uc.uc_stack.ss_sp = ustack;

	uc.uc_stack.ss_size = SIGSTKSZ;

	makecontext(&uc, switch_fn, 0);

	raise(SIGUSR1);



	err = sigaltstack(NULL, &stk);

	if (err) {

		perror("[FAIL]\tsigaltstack()");

		exit(EXIT_FAILURE);

	}

	if (stk.ss_flags != 0) {

		printf("[FAIL]\tss_flags=%i, should be 0\n",

				stk.ss_flags);

		exit(EXIT_FAILURE);

	}

	printf("[OK]\tsigaltstack is enabled after signal\n");



	printf("[OK]\tTest passed\n");

	return 0;

}