The patch titled
Subject: mm/rodata_test: verify test data is unchanged, rather than non-zero
has been added to the -mm mm-unstable branch. Its filename is
mm-rodata_test-verify-test-data-is-unchanged-rather-than-non-zero.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-rodata_test-verify-test-data-is-unchanged-rather-than-non-zero.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Petr Tesarik <ptesarik@xxxxxxxx>
Subject: mm/rodata_test: verify test data is unchanged, rather than non-zero
Date: Tue, 19 Nov 2024 12:37:39 +0100
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@xxxxxxxx
Signed-off-by: Petr Tesarik <ptesarik@xxxxxxxx>
Reviewed-by: Kees Cook <kees@xxxxxxxxxx>
Cc: Jinbum Park <jinb.park7@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/rodata_test.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
--- a/mm/rodata_test.c~mm-rodata_test-verify-test-data-is-unchanged-rather-than-non-zero
+++ a/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;
}
_
Patches currently in -mm which might be from ptesarik@xxxxxxxx are
mm-rodata_test-use-read_once-to-read-const-variable.patch
mm-rodata_test-verify-test-data-is-unchanged-rather-than-non-zero.patch
