diff mbox series

[031/262] kasan: test: bypass __alloc_size checks

Message ID 20211105203612.J6qbXKwVl%akpm@linux-foundation.org (mailing list archive)
State New
Headers show
Series [001/262] scripts/spelling.txt: add more spellings to spelling.txt | expand

Commit Message

Andrew Morton Nov. 5, 2021, 8:36 p.m. UTC 
From: Kees Cook <keescook@chromium.org>
Subject: kasan: test: bypass __alloc_size checks

Intentional overflows, as performed by the KASAN tests, are detected at
compile time[1] (instead of only at run-time) with the addition of
__alloc_size.  Fix this by forcing the compiler into not being able to
trust the size used following the kmalloc()s.

[1] https://lore.kernel.org/lkml/20211005184717.65c6d8eb39350395e387b71f@linux-foundation.org

Link: https://lkml.kernel.org/r/20211006181544.1670992-1-keescook@chromium.org
Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 lib/test_kasan.c        |    8 +++++++-
 lib/test_kasan_module.c |    2 ++
 2 files changed, 9 insertions(+), 1 deletion(-)
diff mbox series

Patch

--- a/lib/test_kasan.c~kasan-test-bypass-__alloc_size-checks
+++ a/lib/test_kasan.c
@@ -440,6 +440,7 @@  static void kmalloc_oob_memset_2(struct
 	ptr = kmalloc(size, GFP_KERNEL);
 	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr);
 
+	OPTIMIZER_HIDE_VAR(size);
 	KUNIT_EXPECT_KASAN_FAIL(test, memset(ptr + size - 1, 0, 2));
 	kfree(ptr);
 }
@@ -452,6 +453,7 @@  static void kmalloc_oob_memset_4(struct
 	ptr = kmalloc(size, GFP_KERNEL);
 	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr);
 
+	OPTIMIZER_HIDE_VAR(size);
 	KUNIT_EXPECT_KASAN_FAIL(test, memset(ptr + size - 3, 0, 4));
 	kfree(ptr);
 }
@@ -464,6 +466,7 @@  static void kmalloc_oob_memset_8(struct
 	ptr = kmalloc(size, GFP_KERNEL);
 	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr);
 
+	OPTIMIZER_HIDE_VAR(size);
 	KUNIT_EXPECT_KASAN_FAIL(test, memset(ptr + size - 7, 0, 8));
 	kfree(ptr);
 }
@@ -476,6 +479,7 @@  static void kmalloc_oob_memset_16(struct
 	ptr = kmalloc(size, GFP_KERNEL);
 	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr);
 
+	OPTIMIZER_HIDE_VAR(size);
 	KUNIT_EXPECT_KASAN_FAIL(test, memset(ptr + size - 15, 0, 16));
 	kfree(ptr);
 }
@@ -488,6 +492,7 @@  static void kmalloc_oob_in_memset(struct
 	ptr = kmalloc(size, GFP_KERNEL);
 	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr);
 
+	OPTIMIZER_HIDE_VAR(size);
 	KUNIT_EXPECT_KASAN_FAIL(test,
 				memset(ptr, 0, size + KASAN_GRANULE_SIZE));
 	kfree(ptr);
@@ -497,7 +502,7 @@  static void kmalloc_memmove_negative_siz
 {
 	char *ptr;
 	size_t size = 64;
-	volatile size_t invalid_size = -2;
+	size_t invalid_size = -2;
 
 	/*
 	 * Hardware tag-based mode doesn't check memmove for negative size.
@@ -510,6 +515,7 @@  static void kmalloc_memmove_negative_siz
 	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr);
 
 	memset((char *)ptr, 0, 64);
+	OPTIMIZER_HIDE_VAR(invalid_size);
 	KUNIT_EXPECT_KASAN_FAIL(test,
 		memmove((char *)ptr, (char *)ptr + 4, invalid_size));
 	kfree(ptr);
--- a/lib/test_kasan_module.c~kasan-test-bypass-__alloc_size-checks
+++ a/lib/test_kasan_module.c
@@ -35,6 +35,8 @@  static noinline void __init copy_user_te
 		return;
 	}
 
+	OPTIMIZER_HIDE_VAR(size);
+
 	pr_info("out-of-bounds in copy_from_user()\n");
 	unused = copy_from_user(kmem, usermem, size + 1);