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Date:      Fri, 30 Nov 2018 22:44:33 +0000 (UTC)
From:      Eric van Gyzen <vangyzen@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r341353 - in head: sys/arm/arm sys/arm64/arm64 sys/riscv/riscv tests/sys/kern
Message-ID:  <201811302244.wAUMiXxl083108@repo.freebsd.org>

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Author: vangyzen
Date: Fri Nov 30 22:44:33 2018
New Revision: 341353
URL: https://svnweb.freebsd.org/changeset/base/341353

Log:
  Fix reporting of SS_ONSTACK
  
  Fix reporting of SS_ONSTACK in nested signal delivery when sigaltstack()
  is used on some architectures.
  
  Add a unit test for this.  I tested the test by introducing the bug
  on amd64.  I did not test it on other architectures.
  
  Reviewed by:	kib
  MFC after:	2 weeks
  Sponsored by:	Dell EMC Isilon
  Differential Revision:	https://reviews.freebsd.org/D18347

Added:
  head/tests/sys/kern/sigaltstack.c   (contents, props changed)
Modified:
  head/sys/arm/arm/machdep.c
  head/sys/arm64/arm64/machdep.c
  head/sys/riscv/riscv/machdep.c
  head/tests/sys/kern/Makefile

Modified: head/sys/arm/arm/machdep.c
==============================================================================
--- head/sys/arm/arm/machdep.c	Fri Nov 30 21:57:02 2018	(r341352)
+++ head/sys/arm/arm/machdep.c	Fri Nov 30 22:44:33 2018	(r341353)
@@ -653,9 +653,9 @@ sendsig(catcher, ksi, mask)
 #endif
 	frame.sf_si = ksi->ksi_info;
 	frame.sf_uc.uc_sigmask = *mask;
-	frame.sf_uc.uc_stack.ss_flags = (td->td_pflags & TDP_ALTSTACK )
-	    ? ((onstack) ? SS_ONSTACK : 0) : SS_DISABLE;
 	frame.sf_uc.uc_stack = td->td_sigstk;
+	frame.sf_uc.uc_stack.ss_flags = (td->td_pflags & TDP_ALTSTACK) != 0 ?
+	    (onstack ? SS_ONSTACK : 0) : SS_DISABLE;
 	mtx_unlock(&psp->ps_mtx);
 	PROC_UNLOCK(td->td_proc);
 

Modified: head/sys/arm64/arm64/machdep.c
==============================================================================
--- head/sys/arm64/arm64/machdep.c	Fri Nov 30 21:57:02 2018	(r341352)
+++ head/sys/arm64/arm64/machdep.c	Fri Nov 30 22:44:33 2018	(r341353)
@@ -661,9 +661,9 @@ sendsig(sig_t catcher, ksiginfo_t *ksi, sigset_t *mask
 	get_fpcontext(td, &frame.sf_uc.uc_mcontext);
 	frame.sf_si = ksi->ksi_info;
 	frame.sf_uc.uc_sigmask = *mask;
-	frame.sf_uc.uc_stack.ss_flags = (td->td_pflags & TDP_ALTSTACK) ?
-	    ((onstack) ? SS_ONSTACK : 0) : SS_DISABLE;
 	frame.sf_uc.uc_stack = td->td_sigstk;
+	frame.sf_uc.uc_stack.ss_flags = (td->td_pflags & TDP_ALTSTACK) != 0 ?
+	    (onstack ? SS_ONSTACK : 0) : SS_DISABLE;
 	mtx_unlock(&psp->ps_mtx);
 	PROC_UNLOCK(td->td_proc);
 

Modified: head/sys/riscv/riscv/machdep.c
==============================================================================
--- head/sys/riscv/riscv/machdep.c	Fri Nov 30 21:57:02 2018	(r341352)
+++ head/sys/riscv/riscv/machdep.c	Fri Nov 30 22:44:33 2018	(r341353)
@@ -587,9 +587,9 @@ sendsig(sig_t catcher, ksiginfo_t *ksi, sigset_t *mask
 	get_fpcontext(td, &frame.sf_uc.uc_mcontext);
 	frame.sf_si = ksi->ksi_info;
 	frame.sf_uc.uc_sigmask = *mask;
-	frame.sf_uc.uc_stack.ss_flags = (td->td_pflags & TDP_ALTSTACK) ?
-	    ((onstack) ? SS_ONSTACK : 0) : SS_DISABLE;
 	frame.sf_uc.uc_stack = td->td_sigstk;
+	frame.sf_uc.uc_stack.ss_flags = (td->td_pflags & TDP_ALTSTACK) != 0 ?
+	    (onstack ? SS_ONSTACK : 0) : SS_DISABLE;
 	mtx_unlock(&psp->ps_mtx);
 	PROC_UNLOCK(td->td_proc);
 

Modified: head/tests/sys/kern/Makefile
==============================================================================
--- head/tests/sys/kern/Makefile	Fri Nov 30 21:57:02 2018	(r341352)
+++ head/tests/sys/kern/Makefile	Fri Nov 30 22:44:33 2018	(r341353)
@@ -10,6 +10,7 @@ ATF_TESTS_C+=	kern_descrip_test
 ATF_TESTS_C+=	ptrace_test
 TEST_METADATA.ptrace_test+=		timeout="15"
 ATF_TESTS_C+=	reaper
+ATF_TESTS_C+=	sigaltstack
 PLAIN_TESTS_C+=	subr_unit_test
 ATF_TESTS_C+=	sys_getrandom
 ATF_TESTS_C+=	unix_passfd_test

Added: head/tests/sys/kern/sigaltstack.c
==============================================================================
--- /dev/null	00:00:00 1970	(empty, because file is newly added)
+++ head/tests/sys/kern/sigaltstack.c	Fri Nov 30 22:44:33 2018	(r341353)
@@ -0,0 +1,115 @@
+/*-
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
+ * Copyright (c) 2018 Eric van Gyzen
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <atf-c.h>
+#include <errno.h>
+#include <signal.h>
+#include <stdbool.h>
+#include <stdlib.h>
+
+/*
+ * TODO add tests for:
+ *
+ * - all error cases
+ * - SS_DISABLE
+ * - no effect without SA_ONSTACK
+ */
+
+static sig_atomic_t disabled_correct = 1;
+static sig_atomic_t level1_correct = -1;
+static sig_atomic_t level2_correct = -1;
+
+static void
+sig_handler(int signo, siginfo_t *info __unused, void *ucp)
+{
+	ucontext_t *uc = ucp;
+
+	// The alternate signal stack is enabled.
+	disabled_correct = disabled_correct &&
+	    (uc->uc_stack.ss_flags & SS_DISABLE) == 0;
+	if (signo == SIGUSR1) {
+		// The thread was NOT running on the alternate signal
+		// stack when this signal arrived.
+		level1_correct = (uc->uc_stack.ss_flags & SS_ONSTACK) == 0;
+		raise(SIGUSR2);
+	} else {
+		// The thread WAS running on the alternate signal
+		// stack when this signal arrived.
+		level2_correct = (uc->uc_stack.ss_flags & SS_ONSTACK) != 0;
+	}
+}
+
+ATF_TC(ss_onstack);
+
+ATF_TC_HEAD(ss_onstack, tc)
+{
+
+	atf_tc_set_md_var(tc, "descr", "Test reporting of SS_ONSTACK");
+}
+
+ATF_TC_BODY(ss_onstack, tc)
+{
+	stack_t ss = {
+		.ss_size = SIGSTKSZ,
+	};
+	stack_t oss = {0};
+
+	ss.ss_sp = malloc(ss.ss_size);
+	ATF_REQUIRE(ss.ss_sp != NULL);
+	ATF_REQUIRE(sigaltstack(&ss, &oss) == 0);
+
+	// There should be no signal stack currently configured.
+	ATF_CHECK(oss.ss_sp == NULL);
+	ATF_CHECK(oss.ss_size == 0);
+	ATF_CHECK((oss.ss_flags & SS_DISABLE) != 0);
+	ATF_CHECK((oss.ss_flags & SS_ONSTACK) == 0);
+
+	struct sigaction sa = {
+		.sa_sigaction = sig_handler,
+		.sa_flags = SA_ONSTACK | SA_SIGINFO,
+	};
+	ATF_REQUIRE(sigemptyset(&sa.sa_mask) == 0);
+	ATF_REQUIRE(sigaction(SIGUSR1, &sa, NULL) == 0);
+	ATF_REQUIRE(sigaction(SIGUSR2, &sa, NULL) == 0);
+	ATF_REQUIRE(raise(SIGUSR1) == 0);
+
+	ATF_CHECK(level1_correct != -1);
+	ATF_CHECK(level1_correct == 1);
+	ATF_CHECK(level2_correct != -1);
+	ATF_CHECK(level2_correct == 1);
+}
+
+ATF_TP_ADD_TCS(tp)
+{
+
+	ATF_TP_ADD_TC(tp, ss_onstack);
+
+	return (atf_no_error());
+}



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