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mm: kmsan: add tests for high-order page freeing

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Add regression tests to verify that KMSAN correctly poisons the full
memory range when freeing pages.

Specifically, verify that accessing the tail pages of a high-order
non-compound allocation triggers a use-after-free report.  This ensures
that the fix "mm: kmsan: Fix poisoning of high-order non-compound pages"
is working as expected.

Also add a test for standard order-0 pages for completeness.

Link: https://lore.kernel.org/all/20260104134348.3544298-1-ryan.roberts@arm.com/
Link: https://lkml.kernel.org/r/20260113091151.4035013-1-glider@google.com
Signed-off-by: Alexander Potapenko <glider@google.com>
Reviewed-by: Ryan Roberts <ryan.roberts@arm.com>
Cc: Dmitriy Vyukov <dvyukov@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Marco Elver <elver@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Alexander Potapenko 2026-01-13 10:11:50 +01:00 committed by Andrew Morton
parent ed581147a4
commit 79ffad20eb
1 changed files with 48 additions and 1 deletions
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49
mm/kmsan/kmsan_test.c
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@ -361,7 +361,7 @@ static void test_init_vmalloc(struct kunit *test)
KUNIT_EXPECT_TRUE(test, report_matches(&expect));
}
/* Test case: ensure that use-after-free reporting works. */
/* Test case: ensure that use-after-free reporting works for kmalloc. */
static void test_uaf(struct kunit *test)
{
EXPECTATION_USE_AFTER_FREE(expect);
@ -378,6 +378,51 @@ static void test_uaf(struct kunit *test)
KUNIT_EXPECT_TRUE(test, report_matches(&expect));
}
static volatile char *test_uaf_pages_helper(int order, int offset)
{
struct page *page;
volatile char *var;
/* Memory is initialized up until __free_pages() thanks to __GFP_ZERO. */
page = alloc_pages(GFP_KERNEL | __GFP_ZERO, order);
var = page_address(page) + offset;
__free_pages(page, order);
return var;
}
/* Test case: ensure that use-after-free reporting works for a freed page. */
static void test_uaf_pages(struct kunit *test)
{
EXPECTATION_USE_AFTER_FREE(expect);
volatile char value;
kunit_info(test, "use-after-free on a freed page (UMR report)\n");
/* Allocate a single page, free it, then try to access it. */
value = *test_uaf_pages_helper(0, 3);
USE(value);
KUNIT_EXPECT_TRUE(test, report_matches(&expect));
}
/* Test case: ensure that UAF reporting works for high order pages. */
static void test_uaf_high_order_pages(struct kunit *test)
{
EXPECTATION_USE_AFTER_FREE(expect);
volatile char value;
kunit_info(test,
"use-after-free on a freed high-order page (UMR report)\n");
/*
* Create a high-order non-compound page, free it, then try to access
* its tail page.
*/
value = *test_uaf_pages_helper(1, PAGE_SIZE + 3);
USE(value);
KUNIT_EXPECT_TRUE(test, report_matches(&expect));
}
/*
* Test case: ensure that uninitialized values are propagated through per-CPU
* memory.
@ -683,6 +728,8 @@ static struct kunit_case kmsan_test_cases[] = {
KUNIT_CASE(test_init_kmsan_vmap_vunmap),
KUNIT_CASE(test_init_vmalloc),
KUNIT_CASE(test_uaf),
KUNIT_CASE(test_uaf_pages),
KUNIT_CASE(test_uaf_high_order_pages),
KUNIT_CASE(test_percpu_propagate),
KUNIT_CASE(test_printk),
KUNIT_CASE(test_init_memcpy),