diff mbox series

kasan: test: Silence allocation warnings from GCC 12

Message ID 20220213183232.4038718-1-keescook@chromium.org (mailing list archive)
State Mainlined
Commit 9622c0be0973f236c8413f936d0d14af5ea2a71e
Headers show
Series kasan: test: Silence allocation warnings from GCC 12 | expand

Commit Message

Kees Cook Feb. 13, 2022, 6:32 p.m. UTC
GCC 12 is able to see more problems with allocation sizes at compile
time, so these must be silenced so the runtime checks will still be
available. Use OPTIMIZER_HIDE_VAR() to silence the new warnings:

lib/test_kasan.c: In function 'ksize_uaf':
lib/test_kasan.c:781:61: warning: array subscript 120 is outside array bounds of 'void[120]' [-Warray-bounds]
  781 |         KUNIT_EXPECT_KASAN_FAIL(test, ((volatile char *)ptr)[size]);
      |                                       ~~~~~~~~~~~~~~~~~~~~~~^~~~~~
lib/test_kasan.c:96:9: note: in definition of macro 'KUNIT_EXPECT_KASAN_FAIL'
   96 |         expression;                                                     \
      |         ^~~~~~~~~~
In function 'kmalloc',
    inlined from 'ksize_uaf' at lib/test_kasan.c:775:8:
./include/linux/slab.h:581:24: note: at offset 120 into object of size 120 allocated by 'kmem_cache_alloc_trace'
  581 |                 return kmem_cache_alloc_trace(
      |                        ^~~~~~~~~~~~~~~~~~~~~~~
  582 |                                 kmalloc_caches[kmalloc_type(flags)][index],
      |                                 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  583 |                                 flags, size);
      |                                 ~~~~~~~~~~~~

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: kasan-dev@googlegroups.com
Signed-off-by: Kees Cook <keescook@chromium.org>
---
 lib/test_kasan.c | 4 ++++
 1 file changed, 4 insertions(+)

Comments

Andrey Konovalov Feb. 16, 2022, 3:26 p.m. UTC | #1
On Sun, Feb 13, 2022 at 7:32 PM Kees Cook <keescook@chromium.org> wrote:
>
> GCC 12 is able to see more problems with allocation sizes at compile
> time, so these must be silenced so the runtime checks will still be
> available. Use OPTIMIZER_HIDE_VAR() to silence the new warnings:
>
> lib/test_kasan.c: In function 'ksize_uaf':

Hm, the warning mentions ksize_uaf, but none of the changes touch it.

> lib/test_kasan.c:781:61: warning: array subscript 120 is outside array bounds of 'void[120]' [-Warray-bounds]
>   781 |         KUNIT_EXPECT_KASAN_FAIL(test, ((volatile char *)ptr)[size]);
>       |                                       ~~~~~~~~~~~~~~~~~~~~~~^~~~~~
> lib/test_kasan.c:96:9: note: in definition of macro 'KUNIT_EXPECT_KASAN_FAIL'
>    96 |         expression;                                                     \
>       |         ^~~~~~~~~~
> In function 'kmalloc',
>     inlined from 'ksize_uaf' at lib/test_kasan.c:775:8:
> ./include/linux/slab.h:581:24: note: at offset 120 into object of size 120 allocated by 'kmem_cache_alloc_trace'
>   581 |                 return kmem_cache_alloc_trace(
>       |                        ^~~~~~~~~~~~~~~~~~~~~~~
>   582 |                                 kmalloc_caches[kmalloc_type(flags)][index],
>       |                                 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>   583 |                                 flags, size);
>       |                                 ~~~~~~~~~~~~
>
> 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: kasan-dev@googlegroups.com
> Signed-off-by: Kees Cook <keescook@chromium.org>
> ---
>  lib/test_kasan.c | 4 ++++
>  1 file changed, 4 insertions(+)
>
> diff --git a/lib/test_kasan.c b/lib/test_kasan.c
> index 26a5c9007653..a19b3d608e3e 100644
> --- a/lib/test_kasan.c
> +++ b/lib/test_kasan.c
> @@ -124,6 +124,7 @@ 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.
> @@ -185,6 +186,7 @@ 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);
> @@ -265,6 +267,7 @@ 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);
>  }
> @@ -748,6 +751,7 @@ static void ksize_unpoisons_memory(struct kunit *test)
>
>         ptr = kmalloc(size, GFP_KERNEL);
>         KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr);
> +       OPTIMIZER_HIDE_VAR(ptr);
>         real_size = ksize(ptr);
>
>         /* This access shouldn't trigger a KASAN report. */
> --
> 2.30.2
>
Kees Cook Feb. 16, 2022, 4:22 p.m. UTC | #2
On Wed, Feb 16, 2022 at 04:26:46PM +0100, Andrey Konovalov wrote:
> On Sun, Feb 13, 2022 at 7:32 PM Kees Cook <keescook@chromium.org> wrote:
> >
> > GCC 12 is able to see more problems with allocation sizes at compile
> > time, so these must be silenced so the runtime checks will still be
> > available. Use OPTIMIZER_HIDE_VAR() to silence the new warnings:
> >
> > lib/test_kasan.c: In function 'ksize_uaf':
> 
> Hm, the warning mentions ksize_uaf, but none of the changes touch it.

Excellent point -- let me go re-test this.

-Kees

> 
> > lib/test_kasan.c:781:61: warning: array subscript 120 is outside array bounds of 'void[120]' [-Warray-bounds]
> >   781 |         KUNIT_EXPECT_KASAN_FAIL(test, ((volatile char *)ptr)[size]);
> >       |                                       ~~~~~~~~~~~~~~~~~~~~~~^~~~~~
> > lib/test_kasan.c:96:9: note: in definition of macro 'KUNIT_EXPECT_KASAN_FAIL'
> >    96 |         expression;                                                     \
> >       |         ^~~~~~~~~~
> > In function 'kmalloc',
> >     inlined from 'ksize_uaf' at lib/test_kasan.c:775:8:
> > ./include/linux/slab.h:581:24: note: at offset 120 into object of size 120 allocated by 'kmem_cache_alloc_trace'
> >   581 |                 return kmem_cache_alloc_trace(
> >       |                        ^~~~~~~~~~~~~~~~~~~~~~~
> >   582 |                                 kmalloc_caches[kmalloc_type(flags)][index],
> >       |                                 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> >   583 |                                 flags, size);
> >       |                                 ~~~~~~~~~~~~
> >
> > 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: kasan-dev@googlegroups.com
> > Signed-off-by: Kees Cook <keescook@chromium.org>
> > ---
> >  lib/test_kasan.c | 4 ++++
> >  1 file changed, 4 insertions(+)
> >
> > diff --git a/lib/test_kasan.c b/lib/test_kasan.c
> > index 26a5c9007653..a19b3d608e3e 100644
> > --- a/lib/test_kasan.c
> > +++ b/lib/test_kasan.c
> > @@ -124,6 +124,7 @@ 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.
> > @@ -185,6 +186,7 @@ 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);
> > @@ -265,6 +267,7 @@ 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);
> >  }
> > @@ -748,6 +751,7 @@ static void ksize_unpoisons_memory(struct kunit *test)
> >
> >         ptr = kmalloc(size, GFP_KERNEL);
> >         KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr);
> > +       OPTIMIZER_HIDE_VAR(ptr);
> >         real_size = ksize(ptr);
> >
> >         /* This access shouldn't trigger a KASAN report. */
> > --
> > 2.30.2
> >
diff mbox series

Patch

diff --git a/lib/test_kasan.c b/lib/test_kasan.c
index 26a5c9007653..a19b3d608e3e 100644
--- a/lib/test_kasan.c
+++ b/lib/test_kasan.c
@@ -124,6 +124,7 @@  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.
@@ -185,6 +186,7 @@  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);
@@ -265,6 +267,7 @@  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);
 }
@@ -748,6 +751,7 @@  static void ksize_unpoisons_memory(struct kunit *test)
 
 	ptr = kmalloc(size, GFP_KERNEL);
 	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr);
+	OPTIMIZER_HIDE_VAR(ptr);
 	real_size = ksize(ptr);
 
 	/* This access shouldn't trigger a KASAN report. */