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sysctl: move u8 register test to lib/test_sysctl.c 

If the test added in commit b5ffbd1396 ("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: b5ffbd1396 ("sysctl: move the extra1/2 boundary check of u8 to sysctl_check_table_array")

Reviewed-by: Kees Cook <kees@kernel.org>
Signed-off-by: Joel Granados <joel.granados@kernel.org>
pull/1250/head
Joel Granados 2025-03-13 22:35:25 +01:00
parent bc4f328ff5
commit 138303ec6c
2 changed files with 66 additions and 49 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

49
kernel/sysctl-test.c
View File

@ -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),
{}
};

66
lib/test_sysctl.c
View File

@ -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);