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: Stas 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: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Stas Sergeev
Ingo Molnar
parent
2a74213838
commit
19fd2868e3
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@ -19,6 +19,7 @@ TARGETS += powerpc
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TARGETS += pstore
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TARGETS += ptrace
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TARGETS += seccomp
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TARGETS += sigaltstack
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TARGETS += size
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TARGETS += static_keys
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TARGETS += sysctl
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@ -0,0 +1,8 @@
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CFLAGS = -Wall
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BINARIES = sas
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all: $(BINARIES)
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include ../lib.mk
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clean:
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rm -rf $(BINARIES)
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@ -0,0 +1,156 @@
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/*
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* Stas Sergeev <stsp@users.sourceforge.net>
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*
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* test sigaltstack(SS_ONSTACK | SS_AUTODISARM)
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* If that succeeds, then swapcontext() can be used inside sighandler safely.
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*
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*/
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#define _GNU_SOURCE
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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 <sys/mman.h>
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#include <ucontext.h>
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#include <alloca.h>
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#include <string.h>
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#include <assert.h>
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#ifndef SS_AUTODISARM
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#define SS_AUTODISARM (1 << 4)
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#endif
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static void *sstack, *ustack;
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static ucontext_t uc, sc;
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static const char *msg = "[OK]\tStack preserved";
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static const char *msg2 = "[FAIL]\tStack corrupted";
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struct stk_data {
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char msg[128];
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int flag;
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};
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void my_usr1(int sig, siginfo_t *si, void *u)
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{
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char *aa;
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int err;
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stack_t stk;
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struct stk_data *p;
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register unsigned long sp asm("sp");
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if (sp < (unsigned long)sstack ||
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sp >= (unsigned long)sstack + SIGSTKSZ) {
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printf("[FAIL]\tSP is not on sigaltstack\n");
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exit(EXIT_FAILURE);
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}
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/* put some data on stack. other sighandler will try to overwrite it */
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aa = alloca(1024);
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assert(aa);
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p = (struct stk_data *)(aa + 512);
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strcpy(p->msg, msg);
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p->flag = 1;
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printf("[RUN]\tsignal USR1\n");
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err = sigaltstack(NULL, &stk);
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if (err) {
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perror("[FAIL]\tsigaltstack()");
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exit(EXIT_FAILURE);
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}
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if (stk.ss_flags != SS_DISABLE)
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printf("[FAIL]\tss_flags=%i, should be SS_DISABLE\n",
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stk.ss_flags);
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else
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printf("[OK]\tsigaltstack is disabled in sighandler\n");
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swapcontext(&sc, &uc);
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printf("%s\n", p->msg);
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if (!p->flag) {
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printf("[RUN]\tAborting\n");
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exit(EXIT_FAILURE);
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}
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}
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void my_usr2(int sig, siginfo_t *si, void *u)
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{
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char *aa;
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struct stk_data *p;
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printf("[RUN]\tsignal USR2\n");
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aa = alloca(1024);
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/* dont run valgrind on this */
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/* try to find the data stored by previous sighandler */
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p = memmem(aa, 1024, msg, strlen(msg));
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if (p) {
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printf("[FAIL]\tsigaltstack re-used\n");
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/* corrupt the data */
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strcpy(p->msg, msg2);
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/* tell other sighandler that his data is corrupted */
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p->flag = 0;
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}
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}
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static void switch_fn(void)
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{
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printf("[RUN]\tswitched to user ctx\n");
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raise(SIGUSR2);
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setcontext(&sc);
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}
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int main(void)
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{
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struct sigaction act;
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stack_t stk;
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int err;
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sigemptyset(&act.sa_mask);
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act.sa_flags = SA_ONSTACK | SA_SIGINFO;
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act.sa_sigaction = my_usr1;
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sigaction(SIGUSR1, &act, NULL);
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act.sa_sigaction = my_usr2;
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sigaction(SIGUSR2, &act, NULL);
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sstack = mmap(NULL, SIGSTKSZ, PROT_READ | PROT_WRITE,
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MAP_PRIVATE | MAP_ANONYMOUS | MAP_STACK, -1, 0);
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if (sstack == MAP_FAILED) {
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perror("mmap()");
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return EXIT_FAILURE;
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}
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stk.ss_sp = sstack;
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stk.ss_size = SIGSTKSZ;
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stk.ss_flags = SS_ONSTACK | SS_AUTODISARM;
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err = sigaltstack(&stk, NULL);
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if (err) {
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perror("[FAIL]\tsigaltstack(SS_ONSTACK | SS_AUTODISARM)");
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stk.ss_flags = SS_ONSTACK;
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}
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err = sigaltstack(&stk, NULL);
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if (err) {
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perror("[FAIL]\tsigaltstack(SS_ONSTACK)");
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return EXIT_FAILURE;
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}
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ustack = mmap(NULL, SIGSTKSZ, PROT_READ | PROT_WRITE,
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MAP_PRIVATE | MAP_ANONYMOUS | MAP_STACK, -1, 0);
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if (ustack == MAP_FAILED) {
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perror("mmap()");
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return EXIT_FAILURE;
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}
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getcontext(&uc);
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uc.uc_link = NULL;
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uc.uc_stack.ss_sp = ustack;
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uc.uc_stack.ss_size = SIGSTKSZ;
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makecontext(&uc, switch_fn, 0);
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raise(SIGUSR1);
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err = sigaltstack(NULL, &stk);
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if (err) {
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perror("[FAIL]\tsigaltstack()");
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exit(EXIT_FAILURE);
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}
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if (stk.ss_flags != 0) {
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printf("[FAIL]\tss_flags=%i, should be 0\n",
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stk.ss_flags);
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exit(EXIT_FAILURE);
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}
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printf("[OK]\tsigaltstack is enabled after signal\n");
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printf("[OK]\tTest passed\n");
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return 0;
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}
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