mm/rodata_test: verify test data is unchanged, rather than non-zero

Verify that the test variable holds the initialization value, rather than
any non-zero value.

Link: https://lkml.kernel.org/r/386ffda192eb4a26f68c526c496afd48a5cd87ce.1732016064.git.ptesarik@suse.com
Signed-off-by: Petr Tesarik <ptesarik@suse.com>
Reviewed-by: Kees Cook <kees@kernel.org>
Cc: Jinbum Park <jinb.park7@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/rodata_test.c b/mm/rodata_test.c
index 3b60425d80fea061ef257a5cf9b0ea610ffa2a5b..e7173fcd210ca3179c9c853fedb8b643f88e9eec 100644 (file)
--- a/mm/rodata_test.c
+++ b/mm/rodata_test.c
@@ -12,7 +12,8 @@
 #include <linux/mm.h>
 #include <asm/sections.h>
 
-static const int rodata_test_data = 0xC3;
+#define TEST_VALUE 0xC3
+static const int rodata_test_data = TEST_VALUE;
 
 void rodata_test(void)
 {
@@ -20,7 +21,7 @@ void rodata_test(void)
 
        /* test 1: read the value */
        /* If this test fails, some previous testrun has clobbered the state */
-       if (!READ_ONCE(rodata_test_data)) {
+       if (unlikely(READ_ONCE(rodata_test_data) != TEST_VALUE)) {
                pr_err("test 1 fails (start data)\n");
                return;
        }
@@ -33,7 +34,7 @@ void rodata_test(void)
        }
 
        /* test 3: check the value hasn't changed */
-       if (READ_ONCE(rodata_test_data) == zero) {
+       if (unlikely(READ_ONCE(rodata_test_data) != TEST_VALUE)) {
                pr_err("test data was changed\n");
                return;
        }