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")
Reviewed-by: Kees Cook <kees@kernel.org>
Signed-off-by: Joel Granados <joel.granados@kernel.org>

diff --git a/kernel/sysctl-test.c b/kernel/sysctl-test.c
index eb2842bd055771ee8a72040f96260bdb0e754ad5..92f94ea28957f48893b0d0d947d73001428fecc7 100644 (file)
--- 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 (file)
--- 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);