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Message-Id: <20250321-jag-test_extra_val-v1-1-a01b3b17dc66@kernel.org>
Date: Fri, 21 Mar 2025 13:47:24 +0100
From: Joel Granados <joel.granados@...nel.org>
To: Kees Cook <kees@...nel.org>, Andrew Morton <akpm@...ux-foundation.org>,
Shuah Khan <shuah@...nel.org>, John Sperbeck <jsperbeck@...gle.com>
Cc: linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
linux-kselftest@...r.kernel.org, Joel Granados <joel.granados@...nel.org>
Subject: [PATCH 1/4] sysctl: move u8 register test to lib/test_sysctl.c
If the test added in commit b5ffbd139688 ("sysctl: move the extra1/2
boundary check of u8 to sysctl_check_table_array") is run as a module, a
lingering reference to the module is left behind, and a 'sysctl -a'
leads to a panic.
To reproduce
CONFIG_KUNIT=y
CONFIG_SYSCTL_KUNIT_TEST=m
Then run these commands:
modprobe sysctl-test
rmmod sysctl-test
sysctl -a
The panic varies but generally looks something like this:
BUG: unable to handle page fault for address: ffffa4571c0c7db4
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 100000067 P4D 100000067 PUD 100351067 PMD 114f5e067 PTE 0
Oops: Oops: 0000 [#1] SMP NOPTI
... ... ...
RIP: 0010:proc_sys_readdir+0x166/0x2c0
... ... ...
Call Trace:
<TASK>
iterate_dir+0x6e/0x140
__se_sys_getdents+0x6e/0x100
do_syscall_64+0x70/0x150
entry_SYSCALL_64_after_hwframe+0x76/0x7e
Move the test to lib/test_sysctl.c where the registration reference is
handled on module exit
'Fixes: b5ffbd139688 ("sysctl: move the extra1/2 boundary check of u8 to
sysctl_check_table_array")'
Signed-off-by: Joel Granados <joel.granados@...nel.org>
---
kernel/sysctl-test.c | 49 --------------------------------------
lib/test_sysctl.c | 66 ++++++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 66 insertions(+), 49 deletions(-)
diff --git a/kernel/sysctl-test.c b/kernel/sysctl-test.c
index eb2842bd055771ee8a72040f96260bdb0e754ad5..92f94ea28957f48893b0d0d947d73001428fecc7 100644
--- a/kernel/sysctl-test.c
+++ b/kernel/sysctl-test.c
@@ -367,54 +367,6 @@ static void sysctl_test_api_dointvec_write_single_greater_int_max(
KUNIT_EXPECT_EQ(test, 0, *((int *)table.data));
}
-/*
- * Test that registering an invalid extra value is not allowed.
- */
-static void sysctl_test_register_sysctl_sz_invalid_extra_value(
- struct kunit *test)
-{
- unsigned char data = 0;
- const struct ctl_table table_foo[] = {
- {
- .procname = "foo",
- .data = &data,
- .maxlen = sizeof(u8),
- .mode = 0644,
- .proc_handler = proc_dou8vec_minmax,
- .extra1 = SYSCTL_FOUR,
- .extra2 = SYSCTL_ONE_THOUSAND,
- },
- };
-
- const struct ctl_table table_bar[] = {
- {
- .procname = "bar",
- .data = &data,
- .maxlen = sizeof(u8),
- .mode = 0644,
- .proc_handler = proc_dou8vec_minmax,
- .extra1 = SYSCTL_NEG_ONE,
- .extra2 = SYSCTL_ONE_HUNDRED,
- },
- };
-
- const struct ctl_table table_qux[] = {
- {
- .procname = "qux",
- .data = &data,
- .maxlen = sizeof(u8),
- .mode = 0644,
- .proc_handler = proc_dou8vec_minmax,
- .extra1 = SYSCTL_ZERO,
- .extra2 = SYSCTL_TWO_HUNDRED,
- },
- };
-
- KUNIT_EXPECT_NULL(test, register_sysctl("foo", table_foo));
- KUNIT_EXPECT_NULL(test, register_sysctl("foo", table_bar));
- KUNIT_EXPECT_NOT_NULL(test, register_sysctl("foo", table_qux));
-}
-
static struct kunit_case sysctl_test_cases[] = {
KUNIT_CASE(sysctl_test_api_dointvec_null_tbl_data),
KUNIT_CASE(sysctl_test_api_dointvec_table_maxlen_unset),
@@ -426,7 +378,6 @@ static struct kunit_case sysctl_test_cases[] = {
KUNIT_CASE(sysctl_test_dointvec_write_happy_single_negative),
KUNIT_CASE(sysctl_test_api_dointvec_write_single_less_int_min),
KUNIT_CASE(sysctl_test_api_dointvec_write_single_greater_int_max),
- KUNIT_CASE(sysctl_test_register_sysctl_sz_invalid_extra_value),
{}
};
diff --git a/lib/test_sysctl.c b/lib/test_sysctl.c
index 4249e0cc8aaff79d7da03aff81b3f9990e9eaac1..54a22e4b134677e022af05df3c75268e7a4a79e7 100644
--- a/lib/test_sysctl.c
+++ b/lib/test_sysctl.c
@@ -37,6 +37,7 @@ static struct {
struct ctl_table_header *test_h_mnterror;
struct ctl_table_header *empty_add;
struct ctl_table_header *empty;
+ struct ctl_table_header *test_u8;
} sysctl_test_headers;
struct test_sysctl_data {
@@ -239,6 +240,65 @@ static int test_sysctl_run_register_empty(void)
return 0;
}
+static const struct ctl_table table_u8_over[] = {
+ {
+ .procname = "u8_over",
+ .data = &test_data.uint_0001,
+ .maxlen = sizeof(u8),
+ .mode = 0644,
+ .proc_handler = proc_dou8vec_minmax,
+ .extra1 = SYSCTL_FOUR,
+ .extra2 = SYSCTL_ONE_THOUSAND,
+ },
+};
+
+static const struct ctl_table table_u8_under[] = {
+ {
+ .procname = "u8_under",
+ .data = &test_data.uint_0001,
+ .maxlen = sizeof(u8),
+ .mode = 0644,
+ .proc_handler = proc_dou8vec_minmax,
+ .extra1 = SYSCTL_NEG_ONE,
+ .extra2 = SYSCTL_ONE_HUNDRED,
+ },
+};
+
+static const struct ctl_table table_u8_valid[] = {
+ {
+ .procname = "u8_valid",
+ .data = &test_data.uint_0001,
+ .maxlen = sizeof(u8),
+ .mode = 0644,
+ .proc_handler = proc_dou8vec_minmax,
+ .extra1 = SYSCTL_ZERO,
+ .extra2 = SYSCTL_TWO_HUNDRED,
+ },
+};
+
+static int test_sysctl_register_u8_extra(void)
+{
+ /* should fail because it's over */
+ sysctl_test_headers.test_u8
+ = register_sysctl("debug/test_sysctl", table_u8_over);
+ if (sysctl_test_headers.test_u8)
+ return -ENOMEM;
+
+ /* should fail because it's under */
+ sysctl_test_headers.test_u8
+ = register_sysctl("debug/test_sysctl", table_u8_under);
+ if (sysctl_test_headers.test_u8)
+ return -ENOMEM;
+
+ /* should not fail because it's valid */
+ sysctl_test_headers.test_u8
+ = register_sysctl("debug/test_sysctl", table_u8_valid);
+ if (!sysctl_test_headers.test_u8)
+ return -ENOMEM;
+
+ return 0;
+}
+
static int __init test_sysctl_init(void)
{
int err;
@@ -256,6 +316,10 @@ static int __init test_sysctl_init(void)
goto out;
err = test_sysctl_run_register_empty();
+ if (err)
+ goto out;
+
+ err = test_sysctl_register_u8_extra();
out:
return err;
@@ -275,6 +339,8 @@ static void __exit test_sysctl_exit(void)
unregister_sysctl_table(sysctl_test_headers.empty);
if (sysctl_test_headers.empty_add)
unregister_sysctl_table(sysctl_test_headers.empty_add);
+ if (sysctl_test_headers.test_u8)
+ unregister_sysctl_table(sysctl_test_headers.test_u8);
}
module_exit(test_sysctl_exit);
--
2.47.2
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