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@kernel.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);