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Subject: [PATCH v5 17/18] kernel/sysctl-test: Add null pointer test for sysctl.c:proc_dointvec()
From:   Brendan Higgins <brendanhiggins@google.com>
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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>
---
Changes Since Last Revision:
 - Iurii did some clean up (thanks Iurii!) as suggested by Stephen Boyd.
---
 kernel/Makefile      |   2 +
 kernel/sysctl-test.c | 242 +++++++++++++++++++++++++++++++++++++++++++
 lib/Kconfig.debug    |  10 ++
 3 files changed, 254 insertions(+)
 create mode 100644 kernel/sysctl-test.c

diff --git a/kernel/Makefile b/kernel/Makefile
index a8d923b5481ba..50fd511cd0ee0 100644
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -114,6 +114,8 @@ 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..cb61ad3c7db63
--- /dev/null
+++ b/kernel/sysctl-test.c
@@ -0,0 +1,242 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * KUnit test of proc sysctl.
+ */
+
+#include <kunit/test.h>
+#include <linux/sysctl.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, (size_t)0, len);
+	len = 1234;
+	KUNIT_EXPECT_EQ(test, 0, proc_dointvec(&table, 1, buffer, &len, &pos));
+	KUNIT_EXPECT_EQ(test, (size_t)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, (size_t)0, len);
+	len = 1234;
+	KUNIT_EXPECT_EQ(test, 0, proc_dointvec(&table, 1, buffer, &len, &pos));
+	KUNIT_EXPECT_EQ(test, (size_t)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, (size_t)0, len);
+	KUNIT_EXPECT_EQ(test, 0, proc_dointvec(&table, 1, buffer, &len, &pos));
+	KUNIT_EXPECT_EQ(test, (size_t)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, (size_t)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, (size_t)pos);
+	KUNIT_EXPECT_EQ(test, 9, ((int *)table.data)[0]);
+}
+
+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, (size_t)pos);
+	KUNIT_EXPECT_EQ(test, -9, ((int *)table.data)[0]);
+}
+
+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,
+			(size_t)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)[0]);
+}
+
+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, (unsigned long)INT_MAX);
+	KUNIT_EXPECT_LT(test, (size_t)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)[0]);
+}
+
+static struct kunit_case sysctl_test_cases[] = {
+	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),
+	{}
+};
+
+static struct kunit_module sysctl_test_module = {
+	.name = "sysctl_test",
+	.test_cases = sysctl_test_cases,
+};
+
+module_test(sysctl_test_module);
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index cbdfae3798965..389b8986f5b77 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -1939,6 +1939,16 @@ config TEST_SYSCTL
 
 	  If unsure, say N.
 
+config SYSCTL_KUNIT_TEST
+	bool "KUnit test for sysctl"
+	depends on KUNIT
+	help
+	  This builds the proc sysctl unit test, which runs on boot. For more
+	  information on KUnit and unit tests in general please refer to the
+	  KUnit documentation in Documentation/dev-tools/kunit/.
+
+	  If unsure, say N.
+
 config TEST_UDELAY
 	tristate "udelay test driver"
 	help
-- 
2.22.0.410.gd8fdbe21b5-goog