diff mbox series

kasan: test: Silence GCC 12 warnings

Message ID 20220608214024.1068451-1-keescook@chromium.org (mailing list archive)
State Mainlined
Commit aaf50b1969d7933a51ea421b11432a7fb90974e3
Headers show
Series kasan: test: Silence GCC 12 warnings | expand

Commit Message

Kees Cook June 8, 2022, 9:40 p.m. UTC
GCC 12 continues to get smarter about array accesses. The KASAN tests
are expecting to explicitly test out-of-bounds conditions at run-time,
so hide the variable from GCC, to avoid warnings like:

../lib/test_kasan.c: In function 'ksize_uaf':
../lib/test_kasan.c:790:61: warning: array subscript 120 is outside array bounds of 'void[120]' [-Warray-bounds]
  790 |         KUNIT_EXPECT_KASAN_FAIL(test, ((volatile char *)ptr)[size]);
      |                                       ~~~~~~~~~~~~~~~~~~~~~~^~~~~~
../lib/test_kasan.c:97:9: note: in definition of macro 'KUNIT_EXPECT_KASAN_FAIL'
   97 |         expression; \
      |         ^~~~~~~~~~

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>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: kasan-dev@googlegroups.com
Signed-off-by: Kees Cook <keescook@chromium.org>
---
 lib/test_kasan.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

Comments

Marco Elver June 9, 2022, 6:54 a.m. UTC | #1
On Wed, 8 Jun 2022 at 23:40, Kees Cook <keescook@chromium.org> wrote:
>
> GCC 12 continues to get smarter about array accesses. The KASAN tests
> are expecting to explicitly test out-of-bounds conditions at run-time,
> so hide the variable from GCC, to avoid warnings like:
>
> ../lib/test_kasan.c: In function 'ksize_uaf':
> ../lib/test_kasan.c:790:61: warning: array subscript 120 is outside array bounds of 'void[120]' [-Warray-bounds]

Since this keeps happening, I wonder if we could just pass
'-Wno-array-bounds' ? We already have 'CFLAGS_test_kasan.o += $(call
cc-disable-warning, vla)'.

Although eventually I'd assume all the OPTIMIZE_HIDE_VAR() should be
in place, and hopefully it'll have been the last one. I leave it to
you.

>   790 |         KUNIT_EXPECT_KASAN_FAIL(test, ((volatile char *)ptr)[size]);
>       |                                       ~~~~~~~~~~~~~~~~~~~~~~^~~~~~
> ../lib/test_kasan.c:97:9: note: in definition of macro 'KUNIT_EXPECT_KASAN_FAIL'
>    97 |         expression; \
>       |         ^~~~~~~~~~
>
> 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>
> Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
> Cc: kasan-dev@googlegroups.com
> Signed-off-by: Kees Cook <keescook@chromium.org>
> ---
>  lib/test_kasan.c | 10 ++++++++++
>  1 file changed, 10 insertions(+)
>
> diff --git a/lib/test_kasan.c b/lib/test_kasan.c
> index c233b1a4e984..58c1b01ccfe2 100644
> --- a/lib/test_kasan.c
> +++ b/lib/test_kasan.c
> @@ -131,6 +131,7 @@ static void kmalloc_oob_right(struct kunit *test)
>         ptr = kmalloc(size, GFP_KERNEL);
>         KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr);
>
> +       OPTIMIZER_HIDE_VAR(ptr);
>         /*
>          * An unaligned access past the requested kmalloc size.
>          * Only generic KASAN can precisely detect these.
> @@ -159,6 +160,7 @@ static void kmalloc_oob_left(struct kunit *test)
>         ptr = kmalloc(size, GFP_KERNEL);
>         KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr);
>
> +       OPTIMIZER_HIDE_VAR(ptr);
>         KUNIT_EXPECT_KASAN_FAIL(test, *ptr = *(ptr - 1));
>         kfree(ptr);
>  }
> @@ -171,6 +173,7 @@ static void kmalloc_node_oob_right(struct kunit *test)
>         ptr = kmalloc_node(size, GFP_KERNEL, 0);
>         KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr);
>
> +       OPTIMIZER_HIDE_VAR(ptr);
>         KUNIT_EXPECT_KASAN_FAIL(test, ptr[0] = ptr[size]);
>         kfree(ptr);
>  }
> @@ -191,6 +194,7 @@ static void kmalloc_pagealloc_oob_right(struct kunit *test)
>         ptr = kmalloc(size, GFP_KERNEL);
>         KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr);
>
> +       OPTIMIZER_HIDE_VAR(ptr);
>         KUNIT_EXPECT_KASAN_FAIL(test, ptr[size + OOB_TAG_OFF] = 0);
>
>         kfree(ptr);
> @@ -271,6 +275,7 @@ static void kmalloc_large_oob_right(struct kunit *test)
>         ptr = kmalloc(size, GFP_KERNEL);
>         KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr);
>
> +       OPTIMIZER_HIDE_VAR(ptr);
>         KUNIT_EXPECT_KASAN_FAIL(test, ptr[size] = 0);
>         kfree(ptr);
>  }
> @@ -410,6 +415,8 @@ static void kmalloc_oob_16(struct kunit *test)
>         ptr2 = kmalloc(sizeof(*ptr2), GFP_KERNEL);
>         KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr2);
>
> +       OPTIMIZER_HIDE_VAR(ptr1);
> +       OPTIMIZER_HIDE_VAR(ptr2);
>         KUNIT_EXPECT_KASAN_FAIL(test, *ptr1 = *ptr2);
>         kfree(ptr1);
>         kfree(ptr2);
> @@ -756,6 +763,8 @@ static void ksize_unpoisons_memory(struct kunit *test)
>         KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr);
>         real_size = ksize(ptr);
>
> +       OPTIMIZER_HIDE_VAR(ptr);
> +
>         /* This access shouldn't trigger a KASAN report. */
>         ptr[size] = 'x';
>
> @@ -778,6 +787,7 @@ static void ksize_uaf(struct kunit *test)
>         KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr);
>         kfree(ptr);
>
> +       OPTIMIZER_HIDE_VAR(ptr);
>         KUNIT_EXPECT_KASAN_FAIL(test, ksize(ptr));
>         KUNIT_EXPECT_KASAN_FAIL(test, ((volatile char *)ptr)[0]);
>         KUNIT_EXPECT_KASAN_FAIL(test, ((volatile char *)ptr)[size]);
> --
> 2.32.0
>
> --
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diff mbox series

Patch

diff --git a/lib/test_kasan.c b/lib/test_kasan.c
index c233b1a4e984..58c1b01ccfe2 100644
--- a/lib/test_kasan.c
+++ b/lib/test_kasan.c
@@ -131,6 +131,7 @@  static void kmalloc_oob_right(struct kunit *test)
 	ptr = kmalloc(size, GFP_KERNEL);
 	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr);
 
+	OPTIMIZER_HIDE_VAR(ptr);
 	/*
 	 * An unaligned access past the requested kmalloc size.
 	 * Only generic KASAN can precisely detect these.
@@ -159,6 +160,7 @@  static void kmalloc_oob_left(struct kunit *test)
 	ptr = kmalloc(size, GFP_KERNEL);
 	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr);
 
+	OPTIMIZER_HIDE_VAR(ptr);
 	KUNIT_EXPECT_KASAN_FAIL(test, *ptr = *(ptr - 1));
 	kfree(ptr);
 }
@@ -171,6 +173,7 @@  static void kmalloc_node_oob_right(struct kunit *test)
 	ptr = kmalloc_node(size, GFP_KERNEL, 0);
 	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr);
 
+	OPTIMIZER_HIDE_VAR(ptr);
 	KUNIT_EXPECT_KASAN_FAIL(test, ptr[0] = ptr[size]);
 	kfree(ptr);
 }
@@ -191,6 +194,7 @@  static void kmalloc_pagealloc_oob_right(struct kunit *test)
 	ptr = kmalloc(size, GFP_KERNEL);
 	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr);
 
+	OPTIMIZER_HIDE_VAR(ptr);
 	KUNIT_EXPECT_KASAN_FAIL(test, ptr[size + OOB_TAG_OFF] = 0);
 
 	kfree(ptr);
@@ -271,6 +275,7 @@  static void kmalloc_large_oob_right(struct kunit *test)
 	ptr = kmalloc(size, GFP_KERNEL);
 	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr);
 
+	OPTIMIZER_HIDE_VAR(ptr);
 	KUNIT_EXPECT_KASAN_FAIL(test, ptr[size] = 0);
 	kfree(ptr);
 }
@@ -410,6 +415,8 @@  static void kmalloc_oob_16(struct kunit *test)
 	ptr2 = kmalloc(sizeof(*ptr2), GFP_KERNEL);
 	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr2);
 
+	OPTIMIZER_HIDE_VAR(ptr1);
+	OPTIMIZER_HIDE_VAR(ptr2);
 	KUNIT_EXPECT_KASAN_FAIL(test, *ptr1 = *ptr2);
 	kfree(ptr1);
 	kfree(ptr2);
@@ -756,6 +763,8 @@  static void ksize_unpoisons_memory(struct kunit *test)
 	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr);
 	real_size = ksize(ptr);
 
+	OPTIMIZER_HIDE_VAR(ptr);
+
 	/* This access shouldn't trigger a KASAN report. */
 	ptr[size] = 'x';
 
@@ -778,6 +787,7 @@  static void ksize_uaf(struct kunit *test)
 	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr);
 	kfree(ptr);
 
+	OPTIMIZER_HIDE_VAR(ptr);
 	KUNIT_EXPECT_KASAN_FAIL(test, ksize(ptr));
 	KUNIT_EXPECT_KASAN_FAIL(test, ((volatile char *)ptr)[0]);
 	KUNIT_EXPECT_KASAN_FAIL(test, ((volatile char *)ptr)[size]);