kasan: add proper page allocator tests

The currently existing page allocator tests rely on kmalloc fallback
with large sizes that is only present for SLUB. Add proper tests that
use alloc/free_pages().

Link: https://linux-review.googlesource.com/id/Ia173d5a1b215fe6b2548d814ef0f4433cf983570
Link: https://lkml.kernel.org/r/a2648930e55ff75b8e700f2e0d905c2b55a67483.1610733117.git.andreyknvl@google.comSigned-off-by: NAndrey Konovalov <andreyknvl@google.com>
Reviewed-by: NMarco Elver <elver@google.com>
Reviewed-by: NAlexander 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: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

lib/test_kasan.c

@@ -147,6 +147,12 @@ static void kmalloc_node_oob_right(struct kunit *test)
 	kfree(ptr);
 }
 
+/*
+ * These kmalloc_pagealloc_* tests try allocating a memory chunk that doesn't
+ * fit into a slab cache and therefore is allocated via the page allocator
+ * fallback. Since this kind of fallback is only implemented for SLUB, these
+ * tests are limited to that allocator.
+ */
 static void kmalloc_pagealloc_oob_right(struct kunit *test)
 {
 	char *ptr;
@@ -154,14 +160,11 @@ static void kmalloc_pagealloc_oob_right(struct kunit *test)
 
 	KASAN_TEST_NEEDS_CONFIG_ON(test, CONFIG_SLUB);
 
-	/*
-	 * Allocate a chunk that does not fit into a SLUB cache to trigger
-	 * the page allocator fallback.
-	 */
 	ptr = kmalloc(size, GFP_KERNEL);
 	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr);
 
 	KUNIT_EXPECT_KASAN_FAIL(test, ptr[size + OOB_TAG_OFF] = 0);
+
 	kfree(ptr);
 }
 
@@ -174,8 +177,8 @@ static void kmalloc_pagealloc_uaf(struct kunit *test)
 
 	ptr = kmalloc(size, GFP_KERNEL);
 	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr);
-
 	kfree(ptr);
+
 	KUNIT_EXPECT_KASAN_FAIL(test, ptr[0] = 0);
 }
 
@@ -192,6 +195,42 @@ static void kmalloc_pagealloc_invalid_free(struct kunit *test)
 	KUNIT_EXPECT_KASAN_FAIL(test, kfree(ptr + 1));
 }
 
+static void pagealloc_oob_right(struct kunit *test)
+{
+	char *ptr;
+	struct page *pages;
+	size_t order = 4;
+	size_t size = (1UL << (PAGE_SHIFT + order));
+
+	/*
+	 * With generic KASAN page allocations have no redzones, thus
+	 * out-of-bounds detection is not guaranteed.
+	 * See https://bugzilla.kernel.org/show_bug.cgi?id=210503.
+	 */
+	KASAN_TEST_NEEDS_CONFIG_OFF(test, CONFIG_KASAN_GENERIC);
+
+	pages = alloc_pages(GFP_KERNEL, order);
+	ptr = page_address(pages);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr);
+
+	KUNIT_EXPECT_KASAN_FAIL(test, ptr[size] = 0);
+	free_pages((unsigned long)ptr, order);
+}
+
+static void pagealloc_uaf(struct kunit *test)
+{
+	char *ptr;
+	struct page *pages;
+	size_t order = 4;
+
+	pages = alloc_pages(GFP_KERNEL, order);
+	ptr = page_address(pages);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr);
+	free_pages((unsigned long)ptr, order);
+
+	KUNIT_EXPECT_KASAN_FAIL(test, ptr[0] = 0);
+}
+
 static void kmalloc_large_oob_right(struct kunit *test)
 {
 	char *ptr;
@@ -903,6 +942,8 @@ static struct kunit_case kasan_kunit_test_cases[] = {
 	KUNIT_CASE(kmalloc_pagealloc_oob_right),
 	KUNIT_CASE(kmalloc_pagealloc_uaf),
 	KUNIT_CASE(kmalloc_pagealloc_invalid_free),
+	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),