Re: [merged mm-stable] kasan-add-atomic-tests.patch removed from -mm tree

Re: [merged mm-stable] kasan-add-atomic-tests.patch removed from -mm tree

[Paul Heidekrüger]

On 21.02.2024 16:03, Andrew Morton wrote:
> 
> The quilt patch titled
>      Subject: kasan: add atomic tests
> has been removed from the -mm tree.  Its filename was
>      kasan-add-atomic-tests.patch
> 
> This patch was dropped because it was merged into the mm-stable branch
> of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
> 
> ------------------------------------------------------
> From: Paul Heidekr??ger <paul.heidekrueger@tum.de>
> Subject: kasan: add atomic tests
> Date: Fri, 2 Feb 2024 11:32:59 +0000
> 
> Test that KASan can detect some unsafe atomic accesses.
> 
> As discussed in the linked thread below, these tests attempt to cover
> the most common uses of atomics and, therefore, aren't exhaustive.
> 
> Link: https://lkml.kernel.org/r/20240202113259.3045705-1-paul.heidekrueger@tum.de
> Link: https://lore.kernel.org/all/20240131210041.686657-1-paul.heidekrueger@tum.de/T/#u
> Signed-off-by: Paul Heidekr??ger <paul.heidekrueger@tum.de>
> Closes: https://bugzilla.kernel.org/show_bug.cgi?id=214055
> Acked-by: Mark Rutland <mark.rutland@arm.com>
> Cc: Marco Elver <elver@google.com>
> Cc: Andrey Konovalov <andreyknvl@gmail.com>
> Cc: Alexander Potapenko <glider@google.com>
> Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
> Cc: Dmitry Vyukov <dvyukov@google.com>
> Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
> ---
> 
>  mm/kasan/kasan_test.c |   79 ++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 79 insertions(+)
> 
> --- a/mm/kasan/kasan_test.c~kasan-add-atomic-tests
> +++ a/mm/kasan/kasan_test.c
> @@ -697,6 +697,84 @@ static void kmalloc_uaf3(struct kunit *t
>  	KUNIT_EXPECT_KASAN_FAIL(test, ((volatile char *)ptr1)[8]);
>  }
>  
> +static void kasan_atomics_helper(struct kunit *test, void *unsafe, void *safe)
> +{
> +	int *i_unsafe = (int *)unsafe;
> +
> +	KUNIT_EXPECT_KASAN_FAIL(test, READ_ONCE(*i_unsafe));
> +	KUNIT_EXPECT_KASAN_FAIL(test, WRITE_ONCE(*i_unsafe, 42));
> +	KUNIT_EXPECT_KASAN_FAIL(test, smp_load_acquire(i_unsafe));
> +	KUNIT_EXPECT_KASAN_FAIL(test, smp_store_release(i_unsafe, 42));
> +
> +	KUNIT_EXPECT_KASAN_FAIL(test, atomic_read(unsafe));
> +	KUNIT_EXPECT_KASAN_FAIL(test, atomic_set(unsafe, 42));
> +	KUNIT_EXPECT_KASAN_FAIL(test, atomic_add(42, unsafe));
> +	KUNIT_EXPECT_KASAN_FAIL(test, atomic_sub(42, unsafe));
> +	KUNIT_EXPECT_KASAN_FAIL(test, atomic_inc(unsafe));
> +	KUNIT_EXPECT_KASAN_FAIL(test, atomic_dec(unsafe));
> +	KUNIT_EXPECT_KASAN_FAIL(test, atomic_and(42, unsafe));
> +	KUNIT_EXPECT_KASAN_FAIL(test, atomic_andnot(42, unsafe));
> +	KUNIT_EXPECT_KASAN_FAIL(test, atomic_or(42, unsafe));
> +	KUNIT_EXPECT_KASAN_FAIL(test, atomic_xor(42, unsafe));
> +	KUNIT_EXPECT_KASAN_FAIL(test, atomic_xchg(unsafe, 42));
> +	KUNIT_EXPECT_KASAN_FAIL(test, atomic_cmpxchg(unsafe, 21, 42));
> +	KUNIT_EXPECT_KASAN_FAIL(test, atomic_try_cmpxchg(unsafe, safe, 42));
> +	KUNIT_EXPECT_KASAN_FAIL(test, atomic_try_cmpxchg(safe, unsafe, 42));
> +	KUNIT_EXPECT_KASAN_FAIL(test, atomic_sub_and_test(42, unsafe));
> +	KUNIT_EXPECT_KASAN_FAIL(test, atomic_dec_and_test(unsafe));
> +	KUNIT_EXPECT_KASAN_FAIL(test, atomic_inc_and_test(unsafe));
> +	KUNIT_EXPECT_KASAN_FAIL(test, atomic_add_negative(42, unsafe));
> +	KUNIT_EXPECT_KASAN_FAIL(test, atomic_add_unless(unsafe, 21, 42));
> +	KUNIT_EXPECT_KASAN_FAIL(test, atomic_inc_not_zero(unsafe));
> +	KUNIT_EXPECT_KASAN_FAIL(test, atomic_inc_unless_negative(unsafe));
> +	KUNIT_EXPECT_KASAN_FAIL(test, atomic_dec_unless_positive(unsafe));
> +	KUNIT_EXPECT_KASAN_FAIL(test, atomic_dec_if_positive(unsafe));
> +
> +	KUNIT_EXPECT_KASAN_FAIL(test, atomic_long_read(unsafe));
> +	KUNIT_EXPECT_KASAN_FAIL(test, atomic_long_set(unsafe, 42));
> +	KUNIT_EXPECT_KASAN_FAIL(test, atomic_long_add(42, unsafe));
> +	KUNIT_EXPECT_KASAN_FAIL(test, atomic_long_sub(42, unsafe));
> +	KUNIT_EXPECT_KASAN_FAIL(test, atomic_long_inc(unsafe));
> +	KUNIT_EXPECT_KASAN_FAIL(test, atomic_long_dec(unsafe));
> +	KUNIT_EXPECT_KASAN_FAIL(test, atomic_long_and(42, unsafe));
> +	KUNIT_EXPECT_KASAN_FAIL(test, atomic_long_andnot(42, unsafe));
> +	KUNIT_EXPECT_KASAN_FAIL(test, atomic_long_or(42, unsafe));
> +	KUNIT_EXPECT_KASAN_FAIL(test, atomic_long_xor(42, unsafe));
> +	KUNIT_EXPECT_KASAN_FAIL(test, atomic_long_xchg(unsafe, 42));
> +	KUNIT_EXPECT_KASAN_FAIL(test, atomic_long_cmpxchg(unsafe, 21, 42));
> +	KUNIT_EXPECT_KASAN_FAIL(test, atomic_long_try_cmpxchg(unsafe, safe, 42));
> +	KUNIT_EXPECT_KASAN_FAIL(test, atomic_long_try_cmpxchg(safe, unsafe, 42));
> +	KUNIT_EXPECT_KASAN_FAIL(test, atomic_long_sub_and_test(42, unsafe));
> +	KUNIT_EXPECT_KASAN_FAIL(test, atomic_long_dec_and_test(unsafe));
> +	KUNIT_EXPECT_KASAN_FAIL(test, atomic_long_inc_and_test(unsafe));
> +	KUNIT_EXPECT_KASAN_FAIL(test, atomic_long_add_negative(42, unsafe));
> +	KUNIT_EXPECT_KASAN_FAIL(test, atomic_long_add_unless(unsafe, 21, 42));
> +	KUNIT_EXPECT_KASAN_FAIL(test, atomic_long_inc_not_zero(unsafe));
> +	KUNIT_EXPECT_KASAN_FAIL(test, atomic_long_inc_unless_negative(unsafe));
> +	KUNIT_EXPECT_KASAN_FAIL(test, atomic_long_dec_unless_positive(unsafe));
> +	KUNIT_EXPECT_KASAN_FAIL(test, atomic_long_dec_if_positive(unsafe));
> +}
> +
> +static void kasan_atomics(struct kunit *test)
> +{
> +	void *a1, *a2;
> +
> +	/*
> +	 * Just as with kasan_bitops_tags(), we allocate 48 bytes of memory such
> +	 * that the following 16 bytes will make up the redzone.
> +	 */
> +	a1 = kzalloc(48, GFP_KERNEL);
> +	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, a1);
> +	a2 = kzalloc(sizeof(int), GFP_KERNEL);
> +	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, a1);
> +
> +	/* Use atomics to access the redzone. */
> +	kasan_atomics_helper(test, a1 + 48, a2);
> +
> +	kfree(a1);
> +	kfree(a2);
> +}
> +
>  static void kmalloc_double_kzfree(struct kunit *test)
>  {
>  	char *ptr;
> @@ -1883,6 +1961,7 @@ static struct kunit_case kasan_kunit_tes
>  	KUNIT_CASE(kasan_strings),
>  	KUNIT_CASE(kasan_bitops_generic),
>  	KUNIT_CASE(kasan_bitops_tags),
> +	KUNIT_CASE(kasan_atomics),
>  	KUNIT_CASE(vmalloc_helpers_tags),
>  	KUNIT_CASE(vmalloc_oob),
>  	KUNIT_CASE(vmap_tags),
> _
> 
> Patches currently in -mm which might be from paul.heidekrueger@tum.de are
> 
> 

Hi Andrew!

There was further discussion around this patch [1], which led to a v3 of the 
above patch but might have gotten lost in the wave of emails.

I'm unsure what the protocol is now; do I send you a new patch for the diff 
between the above patch and the v3 patch, or can you just use v3 instead of the 
above patch?

I hope this doesn't cause too much trouble.

Many thanks,
Paul

[1]: 
https://lore.kernel.org/all/20240212083342.3075850-1-paul.heidekrueger@tum.de/

Re: [merged mm-stable] kasan-add-atomic-tests.patch removed from -mm tree

[Andrew Morton]

On Fri, 23 Feb 2024 21:25:04 +0100 Paul Heidekrüger <paul.heidekrueger@tum.de> wrote:

> I'm unsure what the protocol is now; do I send you a new patch for the diff 
> between the above patch and the v3 patch, or can you just use v3 instead of the 
> above patch?

Yes please.

[PATCH] kasan: fix a2 allocation and remove explicit cast in atomic tests

[Paul Heidekrüger]

Address the additional feedback since "kasan: add atomic tests"
(4e76c8cc3378a20923965e3345f40f6b8ae0bdba) by removing an explicit cast
and fixing the size as well as the check of the allocation of `a2`.

CC: Marco Elver <elver@google.com>
CC: Andrey Konovalov <andreyknvl@gmail.com>
Link: https://lore.kernel.org/all/20240131210041.686657-1-paul.heidekrueger@tum.de/T/#u
Fixes: 4e76c8cc3378a20923965e3345f40f6b8ae0bdba
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=214055
Reviewed-by: Marco Elver <elver@google.com>
Tested-by: Marco Elver <elver@google.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Andrey Konovalov <andreyknvl@gmail.com>
Signed-off-by: Paul Heidekrüger <paul.heidekrueger@tum.de>
---
@Andrew: 
I wasn't sure whether you'd be squashing this patch into v1 or
if it'll end up as a separate commit. Hope this works either way!

Changes PATCH v2 -> PATCH v3:
* Fix the wrong variable being used when checking a2 after allocation
* Add Andrey's reviewed-by tag

Changes PATCH v1 -> PATCH v2:
* Make explicit cast implicit as per Mark's feedback
* Increase the size of the "a2" allocation as per Andrey's feedback
* Add tags 

Changes PATCH RFC v2 -> PATCH v1:
* Remove casts to void*
* Remove i_safe variable
* Add atomic_long_* test cases
* Carry over comment from kasan_bitops_tags()

Changes PATCH RFC v1 -> PATCH RFC v2:
* Adjust size of allocations to make kasan_atomics() work with all KASan modes
* Remove comments and move tests closer to the bitops tests
* For functions taking two addresses as an input, test each address in a separate function call.
* Rename variables for clarity
* Add tests for READ_ONCE(), WRITE_ONCE(), smp_load_acquire() and smp_store_release()

 mm/kasan/kasan_test.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/mm/kasan/kasan_test.c b/mm/kasan/kasan_test.c
index 4ef2280c322c..7f0f87a2c3c4 100644
--- a/mm/kasan/kasan_test.c
+++ b/mm/kasan/kasan_test.c
@@ -1152,7 +1152,7 @@ static void kasan_bitops_tags(struct kunit *test)
 
 static void kasan_atomics_helper(struct kunit *test, void *unsafe, void *safe)
 {
-	int *i_unsafe = (int *)unsafe;
+	int *i_unsafe = unsafe;
 
 	KUNIT_EXPECT_KASAN_FAIL(test, READ_ONCE(*i_unsafe));
 	KUNIT_EXPECT_KASAN_FAIL(test, WRITE_ONCE(*i_unsafe, 42));
@@ -1218,8 +1218,8 @@ static void kasan_atomics(struct kunit *test)
 	 */
 	a1 = kzalloc(48, GFP_KERNEL);
 	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, a1);
-	a2 = kzalloc(sizeof(int), GFP_KERNEL);
-	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, a1);
+	a2 = kzalloc(sizeof(atomic_long_t), GFP_KERNEL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, a2);
 
 	/* Use atomics to access the redzone. */
 	kasan_atomics_helper(test, a1 + 48, a2);
-- 
2.40.1