From: andrey.konovalov@linux.dev
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Andrey Konovalov <andreyknvl@gmail.com>,
Andrey Ryabinin <aryabinin@virtuozzo.com>,
Marco Elver <elver@google.com>,
Dmitry Vyukov <dvyukov@google.com>,
Alexander Potapenko <glider@google.com>,
kasan-dev@googlegroups.com, linux-mm@kvack.org,
linux-kernel@vger.kernel.org
Subject: [PATCH v2 1/8] kasan: test: rework kmalloc_oob_right
Date: Thu, 12 Aug 2021 16:53:28 +0200 [thread overview]
Message-ID: <474aa8b7b538c6737a4c6d0090350af2e1776bef.1628779805.git.andreyknvl@gmail.com> (raw)
In-Reply-To: <cover.1628779805.git.andreyknvl@gmail.com>
From: Andrey Konovalov <andreyknvl@gmail.com>
Rework kmalloc_oob_right() to do these bad access checks:
1. An unaligned access one byte past the requested kmalloc size
(can only be detected by KASAN_GENERIC).
2. An aligned access into the first out-of-bounds granule that falls
within the aligned kmalloc object.
3. Out-of-bounds access past the aligned kmalloc object.
Test #3 deliberately uses a read access to avoid corrupting memory.
Otherwise, this test might lead to crashes with the HW_TAGS mode, as it
neither uses quarantine nor redzones.
Signed-off-by: Andrey Konovalov <andreyknvl@gmail.com>
---
lib/test_kasan.c | 20 ++++++++++++++++++--
1 file changed, 18 insertions(+), 2 deletions(-)
diff --git a/lib/test_kasan.c b/lib/test_kasan.c
index 8f7b0b2f6e11..1bc3cdd2957f 100644
--- a/lib/test_kasan.c
+++ b/lib/test_kasan.c
@@ -122,12 +122,28 @@ static void kasan_test_exit(struct kunit *test)
static void kmalloc_oob_right(struct kunit *test)
{
char *ptr;
- size_t size = 123;
+ size_t size = 128 - KASAN_GRANULE_SIZE - 5;
ptr = kmalloc(size, GFP_KERNEL);
KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr);
- KUNIT_EXPECT_KASAN_FAIL(test, ptr[size + OOB_TAG_OFF] = 'x');
+ /*
+ * An unaligned access past the requested kmalloc size.
+ * Only generic KASAN can precisely detect these.
+ */
+ if (IS_ENABLED(CONFIG_KASAN_GENERIC))
+ KUNIT_EXPECT_KASAN_FAIL(test, ptr[size] = 'x');
+
+ /*
+ * An aligned access into the first out-of-bounds granule that falls
+ * within the aligned kmalloc object.
+ */
+ KUNIT_EXPECT_KASAN_FAIL(test, ptr[size + 5] = 'y');
+
+ /* Out-of-bounds access past the aligned kmalloc object. */
+ KUNIT_EXPECT_KASAN_FAIL(test, ptr[0] =
+ ptr[size + KASAN_GRANULE_SIZE + 5]);
+
kfree(ptr);
}
--
2.25.1
next prev parent reply other threads:[~2021-08-12 14:53 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-12 14:53 [PATCH v2 0/8] kasan: test: avoid crashing the kernel with HW_TAGS andrey.konovalov
2021-08-12 14:53 ` andrey.konovalov [this message]
2021-08-12 14:53 ` [PATCH v2 2/8] kasan: test: avoid writing invalid memory andrey.konovalov
2021-08-12 14:53 ` [PATCH v2 3/8] kasan: test: avoid corrupting memory via memset andrey.konovalov
2021-08-12 14:53 ` [PATCH v2 4/8] kasan: test: disable kmalloc_memmove_invalid_size for HW_TAGS andrey.konovalov
2021-08-12 14:53 ` [PATCH v2 5/8] kasan: test: only do kmalloc_uaf_memset for generic mode andrey.konovalov
2021-08-12 14:56 ` [PATCH v2 6/8] kasan: test: clean up ksize_uaf andrey.konovalov
2021-08-12 15:00 ` [PATCH v2 7/8] kasan: test: avoid corrupting memory in copy_user_test andrey.konovalov
2021-08-12 15:05 ` [PATCH v2 8/8] kasan: test: avoid corrupting memory in kasan_rcu_uaf andrey.konovalov
2021-08-12 15:05 ` [PATCH v2 0/8] kasan: test: avoid crashing the kernel with HW_TAGS Andrey Konovalov
2021-08-12 15:44 ` Marco Elver
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