From: Petr Tesarik <ptesarik@suse.com>
Date: Tue, 19 Nov 2024 11:37:39 +0000 (+0100)
Subject: mm/rodata_test: verify test data is unchanged, rather than non-zero
X-Git-Tag: v6.14-rc1~77^2~287
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=58d534c8c6aa5c5f09fbcb162afb85b91f200560;p=thirdparty%2Fkernel%2Flinux.git

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 3b60425d80fea..e7173fcd210ca 100644
--- 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;
 	}