[PATCH v4 17/18] kernel/sysctl-test: Add null pointer test for sysctl.c:proc_dointvec()

[Brendan Higgins <brendanhiggins@google.com>]

From: Iurii Zaikin <yzaikin@google.com>

KUnit tests for initialized data behavior of proc_dointvec that is
explicitly checked in the code. Includes basic parsing tests including
int min/max overflow.

Signed-off-by: Iurii Zaikin <yzaikin@google.com>
Signed-off-by: Brendan Higgins <brendanhiggins@google.com>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Logan Gunthorpe <logang@deltatee.com>
---
 kernel/Makefile      |   2 +
 kernel/sysctl-test.c | 293 +++++++++++++++++++++++++++++++++++++++++++
 lib/Kconfig.debug    |   6 +
 3 files changed, 301 insertions(+)
 create mode 100644 kernel/sysctl-test.c

diff --git a/kernel/Makefile b/kernel/Makefile
index 6c57e78817dad..c81a8976b6a4b 100644
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -112,6 +112,8 @@ obj-$(CONFIG_HAS_IOMEM) += iomem.o
 obj-$(CONFIG_ZONE_DEVICE) += memremap.o
 obj-$(CONFIG_RSEQ) += rseq.o
 
+obj-$(CONFIG_SYSCTL_KUNIT_TEST) += sysctl-test.o
+
 obj-$(CONFIG_GCC_PLUGIN_STACKLEAK) += stackleak.o
 KASAN_SANITIZE_stackleak.o := n
 KCOV_INSTRUMENT_stackleak.o := n
diff --git a/kernel/sysctl-test.c b/kernel/sysctl-test.c
new file mode 100644
index 0000000000000..fe0f2bae66085
--- /dev/null
+++ b/kernel/sysctl-test.c
@@ -0,0 +1,293 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * KUnit test of proc sysctl.
+ */
+
+#include <kunit/test.h>
+#include <linux/printk.h>
+#include <linux/sysctl.h>
+#include <linux/uaccess.h>
+
+static int i_zero;
+static int i_one_hundred = 100;
+
+struct test_sysctl_data {
+	int int_0001;
+	int int_0002;
+	int int_0003[4];
+
+	unsigned int uint_0001;
+
+	char string_0001[65];
+};
+
+static struct test_sysctl_data test_data = {
+	.int_0001 = 60,
+	.int_0002 = 1,
+
+	.int_0003[0] = 0,
+	.int_0003[1] = 1,
+	.int_0003[2] = 2,
+	.int_0003[3] = 3,
+
+	.uint_0001 = 314,
+
+	.string_0001 = "(none)",
+};
+
+static void sysctl_test_dointvec_null_tbl_data(struct kunit *test)
+{
+	struct ctl_table table = {
+		.procname = "foo",
+		.data		= NULL,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec,
+		.extra1		= &i_zero,
+		.extra2         = &i_one_hundred,
+	};
+	void  *buffer = kunit_kzalloc(test, sizeof(int), GFP_USER);
+	size_t len;
+	loff_t pos;
+
+	len = 1234;
+	KUNIT_EXPECT_EQ(test, 0, proc_dointvec(&table, 0, buffer, &len, &pos));
+	KUNIT_EXPECT_EQ(test, 0, len);
+	len = 1234;
+	KUNIT_EXPECT_EQ(test, 0, proc_dointvec(&table, 1, buffer, &len, &pos));
+	KUNIT_EXPECT_EQ(test, 0, len);
+}
+
+static void sysctl_test_dointvec_table_maxlen_unset(struct kunit *test)
+{
+	struct ctl_table table = {
+		.procname = "foo",
+		.data		= &test_data.int_0001,
+		.maxlen		= 0,
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec,
+		.extra1		= &i_zero,
+		.extra2         = &i_one_hundred,
+	};
+	void  *buffer = kunit_kzalloc(test, sizeof(int), GFP_USER);
+	size_t len;
+	loff_t pos;
+
+	len = 1234;
+	KUNIT_EXPECT_EQ(test, 0, proc_dointvec(&table, 0, buffer, &len, &pos));
+	KUNIT_EXPECT_EQ(test, 0, len);
+	len = 1234;
+	KUNIT_EXPECT_EQ(test, 0, proc_dointvec(&table, 1, buffer, &len, &pos));
+	KUNIT_EXPECT_EQ(test, 0, len);
+}
+
+static void sysctl_test_dointvec_table_len_is_zero(struct kunit *test)
+{
+	struct ctl_table table = {
+		.procname = "foo",
+		.data		= &test_data.int_0001,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec,
+		.extra1		= &i_zero,
+		.extra2         = &i_one_hundred,
+	};
+	void  *buffer = kunit_kzalloc(test, sizeof(int), GFP_USER);
+	size_t len;
+	loff_t pos;
+
+	len = 0;
+	KUNIT_EXPECT_EQ(test, 0, proc_dointvec(&table, 0, buffer, &len, &pos));
+	KUNIT_EXPECT_EQ(test, 0, len);
+	KUNIT_EXPECT_EQ(test, 0, proc_dointvec(&table, 1, buffer, &len, &pos));
+	KUNIT_EXPECT_EQ(test, 0, len);
+}
+
+static void sysctl_test_dointvec_table_read_but_position_set(struct kunit *test)
+{
+	struct ctl_table table = {
+		.procname = "foo",
+		.data		= &test_data.int_0001,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec,
+		.extra1		= &i_zero,
+		.extra2         = &i_one_hundred,
+	};
+	void  *buffer = kunit_kzalloc(test, sizeof(int), GFP_USER);
+	size_t len;
+	loff_t pos;
+
+	len = 1234;
+	pos = 1;
+	KUNIT_EXPECT_EQ(test, 0, proc_dointvec(&table, 0, buffer, &len, &pos));
+	KUNIT_EXPECT_EQ(test, 0, len);
+}
+
+static void sysctl_test_dointvec_happy_single_positive(struct kunit *test)
+{
+	struct ctl_table table = {
+		.procname = "foo",
+		.data		= &test_data.int_0001,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec,
+		.extra1		= &i_zero,
+		.extra2         = &i_one_hundred,
+	};
+	char input[] = "9";
+	size_t len = sizeof(input) - 1;
+	loff_t pos = 0;
+
+	table.data = kunit_kzalloc(test, sizeof(int), GFP_USER);
+	KUNIT_EXPECT_EQ(test, 0, proc_dointvec(&table, 1, input, &len, &pos));
+	KUNIT_EXPECT_EQ(test, sizeof(input) - 1, len);
+	KUNIT_EXPECT_EQ(test, sizeof(input) - 1, pos);
+	KUNIT_EXPECT_EQ(test, 9, *(int *)table.data);
+}
+
+static void sysctl_test_dointvec_happy_single_negative(struct kunit *test)
+{
+	struct ctl_table table = {
+		.procname = "foo",
+		.data		= &test_data.int_0001,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec,
+		.extra1		= &i_zero,
+		.extra2         = &i_one_hundred,
+	};
+	char input[] = "-9";
+	size_t len = sizeof(input) - 1;
+	loff_t pos = 0;
+
+	table.data = kunit_kzalloc(test, sizeof(int), GFP_USER);
+	KUNIT_EXPECT_EQ(test, 0, proc_dointvec(&table, 1, input, &len, &pos));
+	KUNIT_EXPECT_EQ(test, sizeof(input) - 1, len);
+	KUNIT_EXPECT_EQ(test, sizeof(input) - 1, pos);
+	KUNIT_EXPECT_EQ(test, -9, *(int *)table.data);
+}
+
+static void sysctl_test_dointvec_single_less_int_min(struct kunit *test)
+{
+	struct ctl_table table = {
+		.procname = "foo",
+		.data		= &test_data.int_0001,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec,
+		.extra1		= &i_zero,
+		.extra2         = &i_one_hundred,
+	};
+	char input[32];
+	size_t len = sizeof(input) - 1;
+	loff_t pos = 0;
+	unsigned long abs_of_less_than_min = (unsigned long)INT_MAX
+					     - (INT_MAX + INT_MIN) + 1;
+
+	KUNIT_EXPECT_LT(test,
+			snprintf(input, sizeof(input), "-%lu",
+				 abs_of_less_than_min),
+			sizeof(input));
+
+	table.data = kunit_kzalloc(test, sizeof(int), GFP_USER);
+	KUNIT_EXPECT_EQ(test, -EINVAL,
+			proc_dointvec(&table, 1, input, &len, &pos));
+	KUNIT_EXPECT_EQ(test, sizeof(input) - 1, len);
+	KUNIT_EXPECT_EQ(test, 0, *(int *)table.data);
+}
+
+static void sysctl_test_dointvec_single_greater_int_max(struct kunit *test)
+{
+	struct ctl_table table = {
+		.procname = "foo",
+		.data		= &test_data.int_0001,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec,
+		.extra1		= &i_zero,
+		.extra2         = &i_one_hundred,
+	};
+	char input[32];
+	size_t len = sizeof(input) - 1;
+	loff_t pos = 0;
+	unsigned long greater_than_max = (unsigned long)INT_MAX + 1;
+
+	KUNIT_EXPECT_GT(test, greater_than_max, INT_MAX);
+	KUNIT_EXPECT_LT(test, snprintf(input, sizeof(input), "%lu",
+				       greater_than_max),
+			sizeof(input));
+	table.data = kunit_kzalloc(test, sizeof(int), GFP_USER);
+	KUNIT_EXPECT_EQ(test, -EINVAL,
+			proc_dointvec(&table, 1, input, &len, &pos));
+	KUNIT_EXPECT_EQ(test, sizeof(input) - 1, len);
+	KUNIT_EXPECT_EQ(test, 0, *(int *)table.data);
+}
+
+static int sysctl_test_init(struct kunit *test)
+{
+	return 0;
+}
+
+/*
+ * This is run once after each test case, see the comment on example_test_module
+ * for more information.
+ */
+static void sysctl_test_exit(struct kunit *test)
+{
+}
+
+/*
+ * Here we make a list of all the test cases we want to add to the test module
+ * below.
+ */
+static struct kunit_case sysctl_test_cases[] = {
+	/*
+	 * This is a helper to create a test case object from a test case
+	 * function; its exact function is not important to understand how to
+	 * use KUnit, just know that this is how you associate test cases with a
+	 * test module.
+	 */
+	KUNIT_CASE(sysctl_test_dointvec_null_tbl_data),
+	KUNIT_CASE(sysctl_test_dointvec_table_maxlen_unset),
+	KUNIT_CASE(sysctl_test_dointvec_table_len_is_zero),
+	KUNIT_CASE(sysctl_test_dointvec_table_read_but_position_set),
+	KUNIT_CASE(sysctl_test_dointvec_happy_single_positive),
+	KUNIT_CASE(sysctl_test_dointvec_happy_single_negative),
+	KUNIT_CASE(sysctl_test_dointvec_single_less_int_min),
+	KUNIT_CASE(sysctl_test_dointvec_single_greater_int_max),
+	{},
+};
+
+/*
+ * This defines a suite or grouping of tests.
+ *
+ * Test cases are defined as belonging to the suite by adding them to
+ * `test_cases`.
+ *
+ * Often it is desirable to run some function which will set up things which
+ * will be used by every test; this is accomplished with an `init` function
+ * which runs before each test case is invoked. Similarly, an `exit` function
+ * may be specified which runs after every test case and can be used to for
+ * cleanup. For clarity, running tests in a test module would behave as follows:
+ *
+ * module.init(test);
+ * module.test_case[0](test);
+ * module.exit(test);
+ * module.init(test);
+ * module.test_case[1](test);
+ * module.exit(test);
+ * ...;
+ */
+static struct kunit_module sysctl_test_module = {
+	.name = "sysctl_test",
+	.init = sysctl_test_init,
+	.exit = sysctl_test_exit,
+	.test_cases = sysctl_test_cases,
+};
+
+/*
+ * This registers the above test module telling KUnit that this is a suite of
+ * tests that need to be run.
+ */
+module_test(sysctl_test_module);
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index d5a4a4036d2f8..772af4ec70111 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -1908,6 +1908,12 @@ config TEST_SYSCTL
 
 	  If unsure, say N.
 
+config SYSCTL_KUNIT_TEST
+	bool "KUnit test for sysctl"
+	depends on KUNIT
+	help
+	  Enables KUnit sysctl test.
+
 config TEST_UDELAY
 	tristate "udelay test driver"
 	help
-- 
2.21.0.1020.gf2820cf01a-goog