Add a regress test for the end of lock range ambiguity bug.

2 files changed, 99 insertions, 2 deletions

diff --git a/regress/sys/kern/flock/Makefile b/regress/sys/kern/flock/Makefile
index 2bf4167e0b1..46556e05f91 100644
--- a/regress/sys/kern/flock/Makefile
+++ b/regress/sys/kern/flock/Makefile
@@ -1,4 +1,4 @@
-#	$OpenBSD: Makefile,v 1.12 2022/04/27 18:02:05 anton Exp $
+#	$OpenBSD: Makefile,v 1.13 2022/06/01 14:21:50 visa Exp $
 
 PROGS+=		flock
 SRCS_flock=	flock.c util.c
@@ -9,7 +9,7 @@ SRCS_lockf=	lockf.c util.c
 
 WARNINGS=	yes
 
-TESTS_FLOCK!=	jot 25 1
+TESTS_FLOCK!=	jot 26 1
 .for t in ${TESTS_FLOCK}
 run-flock-$t: flock
 	./flock ${LOCKFLAGS} $t
diff --git a/regress/sys/kern/flock/flock.c b/regress/sys/kern/flock/flock.c
index f4fa317600e..f8ec8a0c5d1 100644
--- a/regress/sys/kern/flock/flock.c
+++ b/regress/sys/kern/flock/flock.c
@@ -1760,6 +1760,102 @@ test25(int fd)
 	SUCCEED;
 }
 
+/*
+ * Test 26 - range end point ambiguity regression
+ *
+ * When a new lock range [start, LLONG_MAX] overlapped with an existing range,
+ * kernel's lock data structure could become inconsistent.
+ */
+static int
+test26(int fd)
+{
+	struct flock fl;
+	pid_t pid;
+	int res, status;
+
+	/* Lock the whole range. */
+	fl.l_start = 0;
+	fl.l_len = 0;
+	fl.l_pid = 0;
+	fl.l_type = F_RDLCK;
+	fl.l_whence = SEEK_SET;
+	res = fcntl(fd, F_SETLK, &fl);
+	FAIL(res != 0);
+
+	/*
+	 * Split the range at the end.
+	 * This should be handled as if l_len == 0.
+	 */
+	fl.l_start = LLONG_MAX;
+	fl.l_len = 1;
+	fl.l_pid = 0;
+	fl.l_type = F_WRLCK;
+	fl.l_whence = SEEK_SET;
+	res = fcntl(fd, F_SETLK, &fl);
+	FAIL(res != 0);
+
+	/* Check the resulting ranges. */
+	pid = fork();
+	if (pid == -1)
+		err(1, "fork");
+	if (pid == 0) {
+		fl.l_start = 0;
+		fl.l_len = 0;
+		fl.l_type = F_WRLCK;
+		fl.l_whence = SEEK_SET;
+		res = fcntl(fd, F_GETLK, &fl);
+		FAIL(res != 0);
+		FAIL(fl.l_type != F_RDLCK);
+		FAIL(fl.l_start != 0);
+		FAIL(fl.l_len != LLONG_MAX);
+
+		fl.l_start = LLONG_MAX;
+		fl.l_len = 0;
+		fl.l_type = F_WRLCK;
+		fl.l_whence = SEEK_SET;
+		res = fcntl(fd, F_GETLK, &fl);
+		FAIL(res != 0);
+		FAIL(fl.l_type != F_WRLCK);
+		FAIL(fl.l_start != LLONG_MAX);
+		FAIL(fl.l_len != 0);
+
+		_exit(0);
+	}
+	status = safe_waitpid(pid);
+	FAIL(status != 0);
+
+	/* Release all locks. */
+	fl.l_start = 0;
+	fl.l_len = 0;
+	fl.l_pid = 0;
+	fl.l_type = F_UNLCK;
+	fl.l_whence = SEEK_SET;
+	res = fcntl(fd, F_SETLK, &fl);
+	FAIL(res != 0);
+
+	/* Check the resulting ranges. */
+	pid = fork();
+	if (pid == -1)
+		err(1, "fork");
+	if (pid == 0) {
+		fl.l_start = 0;
+		fl.l_len = 0;
+		fl.l_type = F_WRLCK;
+		fl.l_whence = SEEK_SET;
+		res = fcntl(fd, F_GETLK, &fl);
+		FAIL(res != 0);
+		FAIL(fl.l_type != F_UNLCK);
+		FAIL(fl.l_start != 0);
+		FAIL(fl.l_len != 0);
+
+		_exit(0);
+	}
+	status = safe_waitpid(pid);
+	FAIL(status != 0);
+
+	SUCCEED;
+}
+
 static struct test tests[] = {
 	{	test1,		0	},
 	{	test2,		0	},
@@ -1786,6 +1882,7 @@ static struct test tests[] = {
 	{	test23,		0	},
 	{	test24,		0	},
 	{	test25,		0	},
+	{	test26,		0	},
 };
 
 static int test_count = sizeof(tests) / sizeof(tests[0]);