linux-kernel - [PATCH v2 12/14] kasan: add proper page allocator tests

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Message-Id: <b7b0ca13a5a4d0d9d8b2fe88a9c3c154bb885294.1610554432.git.andreyknvl@google.com>
Date:   Wed, 13 Jan 2021 17:21:39 +0100
From:   Andrey Konovalov <andreyknvl@...gle.com>
To:     Catalin Marinas <catalin.marinas@....com>,
        Vincenzo Frascino <vincenzo.frascino@....com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Alexander Potapenko <glider@...gle.com>,
        Marco Elver <elver@...gle.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Will Deacon <will.deacon@....com>,
        Andrey Ryabinin <aryabinin@...tuozzo.com>,
        Peter Collingbourne <pcc@...gle.com>,
        Evgenii Stepanov <eugenis@...gle.com>,
        Branislav Rankov <Branislav.Rankov@....com>,
        Kevin Brodsky <kevin.brodsky@....com>,
        kasan-dev@...glegroups.com, linux-arm-kernel@...ts.infradead.org,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        Andrey Konovalov <andreyknvl@...gle.com>
Subject: [PATCH v2 12/14] 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
Reviewed-by: Marco Elver <elver@...gle.com>
Reviewed-by: Alexander Potapenko <glider@...gle.com>
Signed-off-by: Andrey Konovalov <andreyknvl@...gle.com>
---
 lib/test_kasan.c | 51 +++++++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 46 insertions(+), 5 deletions(-)

diff --git a/lib/test_kasan.c b/lib/test_kasan.c
index 710e714dc0cb..5e3d054e5b8c 100644
--- a/lib/test_kasan.c
+++ b/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),
-- 
2.30.0.284.gd98b1dd5eaa7-goog