[src/trunk]: src/tests/lib/libc/sys Add a regression test for PR kern/52239, ...

[gson <gson%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/45bdbf6cce1e
branches:  trunk
changeset: 364675:45bdbf6cce1e
user:      gson <gson%NetBSD.org@localhost>
date:      Wed Apr 06 10:02:55 2022 +0000

description:
Add a regression test for PR kern/52239, "Changing protections of
already mmap'ed region can fail", based on the test program in the PR.

diffstat:

 tests/lib/libc/sys/Makefile |   3 +-
 tests/lib/libc/sys/t_mmap.c |  65 +++++++++++++++++++++++++++++++++++++++++++-
 2 files changed, 65 insertions(+), 3 deletions(-)

diffs (117 lines):

diff -r 0cae926f475c -r 45bdbf6cce1e tests/lib/libc/sys/Makefile
--- a/tests/lib/libc/sys/Makefile       Wed Apr 06 03:23:38 2022 +0000
+++ b/tests/lib/libc/sys/Makefile       Wed Apr 06 10:02:55 2022 +0000
@@ -1,4 +1,4 @@
-# $NetBSD: Makefile,v 1.70 2021/11/01 14:33:41 hannken Exp $
+# $NetBSD: Makefile,v 1.71 2022/04/06 10:02:55 gson Exp $
 
 MKMAN= no
 
@@ -97,6 +97,7 @@
 
 LDADD.t_eventfd+=      -lpthread
 LDADD.t_getpid+=       -lpthread
+LDADD.t_mmap+=         -lpthread
 LDADD.t_timerfd+=      -lpthread
 
 LDADD.t_ptrace_sigchld+=       -pthread -lm
diff -r 0cae926f475c -r 45bdbf6cce1e tests/lib/libc/sys/t_mmap.c
--- a/tests/lib/libc/sys/t_mmap.c       Wed Apr 06 03:23:38 2022 +0000
+++ b/tests/lib/libc/sys/t_mmap.c       Wed Apr 06 10:02:55 2022 +0000
@@ -1,4 +1,4 @@
-/* $NetBSD: t_mmap.c,v 1.16 2022/04/05 15:59:22 gson Exp $ */
+/* $NetBSD: t_mmap.c,v 1.17 2022/04/06 10:02:55 gson Exp $ */
 
 /*-
  * Copyright (c) 2011 The NetBSD Foundation, Inc.
@@ -55,7 +55,7 @@
  * SUCH DAMAGE.
  */
 #include <sys/cdefs.h>
-__RCSID("$NetBSD: t_mmap.c,v 1.16 2022/04/05 15:59:22 gson Exp $");
+__RCSID("$NetBSD: t_mmap.c,v 1.17 2022/04/06 10:02:55 gson Exp $");
 
 #include <sys/param.h>
 #include <sys/disklabel.h>
@@ -74,6 +74,7 @@
 #include <string.h>
 #include <unistd.h>
 #include <paths.h>
+#include <pthread.h>
 
 static long    page = 0;
 static char    path[] = "mmap";
@@ -413,6 +414,65 @@
        (void)unlink(path);
 }
 
+ATF_TC(mmap_reprotect_race);
+
+ATF_TC_HEAD(mmap_reprotect_race, tc)
+{
+       atf_tc_set_md_var(tc, "descr", "Test for the race condition of PR 52239");
+}
+
+const int mmap_reprotect_race_npages = 13;
+const int mmap_reprotect_iterations = 1000000;
+
+static void *
+mmap_reprotect_race_thread(void *arg)
+{
+       int i, r;
+       void *p;
+
+       for (i = 0; i < mmap_reprotect_iterations; i++) {
+               /* Get some unrelated memory */
+               p = mmap(0, mmap_reprotect_race_npages * page,
+                        PROT_READ|PROT_WRITE, MAP_ANON|MAP_PRIVATE, -1, 0);
+               ATF_REQUIRE(p);
+               r = munmap(p, mmap_reprotect_race_npages * page);
+               ATF_REQUIRE(r == 0);
+       }
+       return 0;
+}
+
+ATF_TC_BODY(mmap_reprotect_race, tc)
+{
+       pthread_t thread;
+       void *p, *q;
+       int i, r;
+
+       r = pthread_create(&thread, 0, mmap_reprotect_race_thread, 0);
+       ATF_REQUIRE(r == 0);
+
+       for (i = 0; i < mmap_reprotect_iterations; i++) {
+               /* Get a placeholder region */
+               p = mmap(0, mmap_reprotect_race_npages * page,
+                        PROT_NONE, MAP_ANON|MAP_PRIVATE, -1, 0);
+               if (p == MAP_FAILED)
+                       atf_tc_fail("mmap: %s", strerror(errno));
+
+               /* Upgrade placeholder to read/write access */
+               q = mmap(p, mmap_reprotect_race_npages * page,
+                        PROT_READ|PROT_WRITE,
+                        MAP_ANON|MAP_PRIVATE|MAP_FIXED, -1, 0);
+               if (q == MAP_FAILED)
+                       atf_tc_fail("update mmap: %s", strerror(errno));
+               ATF_REQUIRE(q == p);
+
+               /* Free it */
+               r = munmap(q, mmap_reprotect_race_npages * page);
+               if (r != 0)
+                       atf_tc_fail("munmap: %s", strerror(errno));
+       }
+       pthread_join(thread, NULL);
+}
+
 ATF_TC_WITH_CLEANUP(mmap_truncate);
 ATF_TC_HEAD(mmap_truncate, tc)
 {
@@ -570,6 +630,7 @@
        ATF_TP_ADD_TC(tp, mmap_prot_1);
        ATF_TP_ADD_TC(tp, mmap_prot_2);
        ATF_TP_ADD_TC(tp, mmap_prot_3);
+       ATF_TP_ADD_TC(tp, mmap_reprotect_race);
        ATF_TP_ADD_TC(tp, mmap_truncate);
        ATF_TP_ADD_TC(tp, mmap_truncate_signal);
        ATF_TP_ADD_TC(tp, mmap_va0);