Commit b87c28b9 authored by Andrey Konovalov's avatar Andrey Konovalov Committed by Linus Torvalds
Browse files

kasan: rework krealloc tests 

This patch reworks KASAN-KUnit tests for krealloc() to:

1. Check both slab and page_alloc based krealloc() implementations.
2. Allow at least one full granule to fit between old and new sizes for
   each KASAN mode, and check accesses to that granule accordingly.

Link: https://lkml.kernel.org/r/c707f128a2bb9f2f05185d1eb52192cf179cf4fa.1612546384.git.andreyknvl@google.com


Signed-off-by: default avatarAndrey Konovalov <andreyknvl@google.com>
Reviewed-by: default avatarMarco Elver <elver@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Branislav Rankov <Branislav.Rankov@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Evgenii Stepanov <eugenis@google.com>
Cc: Kevin Brodsky <kevin.brodsky@arm.com>
Cc: Peter Collingbourne <pcc@google.com>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 200072ce

lib/test_kasan.c

+81 −10
Original line number Diff line number Diff line
@@ -252,11 +252,14 @@ static void kmalloc_large_oob_right(struct kunit *test) 
	kfree(ptr);

}



static void kmalloc_oob_krealloc_more(struct kunit *test)

static void krealloc_more_oob_helper(struct kunit *test,

					size_t size1, size_t size2)

{

	char *ptr1, *ptr2;

	size_t size1 = 17;

	size_t size2 = 19;

	size_t middle;



	KUNIT_ASSERT_LT(test, size1, size2);

	middle = size1 + (size2 - size1) / 2;



	ptr1 = kmalloc(size1, GFP_KERNEL);

	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr1);
@@ -264,15 +267,31 @@ static void kmalloc_oob_krealloc_more(struct kunit *test) 
	ptr2 = krealloc(ptr1, size2, GFP_KERNEL);

	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr2);



	KUNIT_EXPECT_KASAN_FAIL(test, ptr2[size2 + OOB_TAG_OFF] = 'x');

	/* All offsets up to size2 must be accessible. */

	ptr2[size1 - 1] = 'x';

	ptr2[size1] = 'x';

	ptr2[middle] = 'x';

	ptr2[size2 - 1] = 'x';



	/* Generic mode is precise, so unaligned size2 must be inaccessible. */

	if (IS_ENABLED(CONFIG_KASAN_GENERIC))

		KUNIT_EXPECT_KASAN_FAIL(test, ptr2[size2] = 'x');



	/* For all modes first aligned offset after size2 must be inaccessible. */

	KUNIT_EXPECT_KASAN_FAIL(test,

		ptr2[round_up(size2, KASAN_GRANULE_SIZE)] = 'x');



	kfree(ptr2);

}



static void kmalloc_oob_krealloc_less(struct kunit *test)

static void krealloc_less_oob_helper(struct kunit *test,

					size_t size1, size_t size2)

{

	char *ptr1, *ptr2;

	size_t size1 = 17;

	size_t size2 = 15;

	size_t middle;



	KUNIT_ASSERT_LT(test, size2, size1);

	middle = size2 + (size1 - size2) / 2;



	ptr1 = kmalloc(size1, GFP_KERNEL);

	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr1);
@@ -280,10 +299,60 @@ static void kmalloc_oob_krealloc_less(struct kunit *test) 
	ptr2 = krealloc(ptr1, size2, GFP_KERNEL);

	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr2);



	KUNIT_EXPECT_KASAN_FAIL(test, ptr2[size2 + OOB_TAG_OFF] = 'x');

	/* Must be accessible for all modes. */

	ptr2[size2 - 1] = 'x';



	/* Generic mode is precise, so unaligned size2 must be inaccessible. */

	if (IS_ENABLED(CONFIG_KASAN_GENERIC))

		KUNIT_EXPECT_KASAN_FAIL(test, ptr2[size2] = 'x');



	/* For all modes first aligned offset after size2 must be inaccessible. */

	KUNIT_EXPECT_KASAN_FAIL(test,

		ptr2[round_up(size2, KASAN_GRANULE_SIZE)] = 'x');



	/*

	 * For all modes all size2, middle, and size1 should land in separate

	 * granules and thus the latter two offsets should be inaccessible.

	 */

	KUNIT_EXPECT_LE(test, round_up(size2, KASAN_GRANULE_SIZE),

				round_down(middle, KASAN_GRANULE_SIZE));

	KUNIT_EXPECT_LE(test, round_up(middle, KASAN_GRANULE_SIZE),

				round_down(size1, KASAN_GRANULE_SIZE));

	KUNIT_EXPECT_KASAN_FAIL(test, ptr2[middle] = 'x');

	KUNIT_EXPECT_KASAN_FAIL(test, ptr2[size1 - 1] = 'x');

	KUNIT_EXPECT_KASAN_FAIL(test, ptr2[size1] = 'x');



	kfree(ptr2);

}



static void krealloc_more_oob(struct kunit *test)

{

	krealloc_more_oob_helper(test, 201, 235);

}



static void krealloc_less_oob(struct kunit *test)

{

	krealloc_less_oob_helper(test, 235, 201);

}



static void krealloc_pagealloc_more_oob(struct kunit *test)

{

	/* page_alloc fallback in only implemented for SLUB. */

	KASAN_TEST_NEEDS_CONFIG_ON(test, CONFIG_SLUB);



	krealloc_more_oob_helper(test, KMALLOC_MAX_CACHE_SIZE + 201,

					KMALLOC_MAX_CACHE_SIZE + 235);

}



static void krealloc_pagealloc_less_oob(struct kunit *test)

{

	/* page_alloc fallback in only implemented for SLUB. */

	KASAN_TEST_NEEDS_CONFIG_ON(test, CONFIG_SLUB);



	krealloc_less_oob_helper(test, KMALLOC_MAX_CACHE_SIZE + 235,

					KMALLOC_MAX_CACHE_SIZE + 201);

}



static void kmalloc_oob_16(struct kunit *test)

{

	struct {
@@ -977,8 +1046,10 @@ static struct kunit_case kasan_kunit_test_cases[] = { 
	KUNIT_CASE(pagealloc_oob_right),

	KUNIT_CASE(pagealloc_uaf),

	KUNIT_CASE(kmalloc_large_oob_right),

	KUNIT_CASE(kmalloc_oob_krealloc_more),

	KUNIT_CASE(kmalloc_oob_krealloc_less),

	KUNIT_CASE(krealloc_more_oob),

	KUNIT_CASE(krealloc_less_oob),

	KUNIT_CASE(krealloc_pagealloc_more_oob),

	KUNIT_CASE(krealloc_pagealloc_less_oob),

	KUNIT_CASE(kmalloc_oob_16),

	KUNIT_CASE(kmalloc_uaf_16),

	KUNIT_CASE(kmalloc_oob_in_memset),