linux-kernel - Re: [PATCH v2 13/14] kasan: add a test for kmem_cache_alloc/free

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Date:   Wed, 13 Jan 2021 17:37:58 +0100
From:   Marco Elver <elver@...gle.com>
To:     Andrey Konovalov <andreyknvl@...gle.com>
Cc:     Catalin Marinas <catalin.marinas@....com>,
        Vincenzo Frascino <vincenzo.frascino@....com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Alexander Potapenko <glider@...gle.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Will Deacon <will.deacon@....com>,
        Andrey Ryabinin <aryabinin@...tuozzo.com>,
        Peter Collingbourne <pcc@...gle.com>,
        Evgenii Stepanov <eugenis@...gle.com>,
        Branislav Rankov <Branislav.Rankov@....com>,
        Kevin Brodsky <kevin.brodsky@....com>,
        kasan-dev <kasan-dev@...glegroups.com>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        Linux Memory Management List <linux-mm@...ck.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 13/14] kasan: add a test for kmem_cache_alloc/free_bulk

On Wed, 13 Jan 2021 at 17:22, Andrey Konovalov <andreyknvl@...gle.com> wrote:
>
> Add a test for kmem_cache_alloc/free_bulk to make sure there are now
> false-positives when these functions are used.

s/now/no/ (but by itself doesn't necessarily demand a v3)

> Link: https://linux-review.googlesource.com/id/I2a8bf797aecf81baeac61380c567308f319e263d
> Signed-off-by: Andrey Konovalov <andreyknvl@...gle.com>
> ---
>  lib/test_kasan.c | 39 ++++++++++++++++++++++++++++++++++-----
>  1 file changed, 34 insertions(+), 5 deletions(-)
>
> diff --git a/lib/test_kasan.c b/lib/test_kasan.c
> index 5e3d054e5b8c..d9f9a93922d5 100644
> --- a/lib/test_kasan.c
> +++ b/lib/test_kasan.c
> @@ -479,10 +479,11 @@ static void kmem_cache_oob(struct kunit *test)
>  {
>         char *p;
>         size_t size = 200;
> -       struct kmem_cache *cache = kmem_cache_create("test_cache",
> -                                               size, 0,
> -                                               0, NULL);
> +       struct kmem_cache *cache;
> +
> +       cache = kmem_cache_create("test_cache", size, 0, 0, NULL);
>         KUNIT_ASSERT_NOT_ERR_OR_NULL(test, cache);
> +
>         p = kmem_cache_alloc(cache, GFP_KERNEL);
>         if (!p) {
>                 kunit_err(test, "Allocation failed: %s\n", __func__);
> @@ -491,11 +492,12 @@ static void kmem_cache_oob(struct kunit *test)
>         }
>
>         KUNIT_EXPECT_KASAN_FAIL(test, *p = p[size + OOB_TAG_OFF]);
> +
>         kmem_cache_free(cache, p);
>         kmem_cache_destroy(cache);
>  }
>
> -static void memcg_accounted_kmem_cache(struct kunit *test)
> +static void kmem_cache_accounted(struct kunit *test)
>  {
>         int i;
>         char *p;
> @@ -522,6 +524,32 @@ static void memcg_accounted_kmem_cache(struct kunit *test)
>         kmem_cache_destroy(cache);
>  }
>
> +static void kmem_cache_bulk(struct kunit *test)
> +{
> +       struct kmem_cache *cache;
> +       size_t size = 200;
> +       size_t p_size = 10;

s/p_size/ARRAY_SIZE(p)/
?

> +       char *p[10];
> +       bool ret;
> +       int i;
> +
> +       cache = kmem_cache_create("test_cache", size, 0, 0, NULL);
> +       KUNIT_ASSERT_NOT_ERR_OR_NULL(test, cache);
> +
> +       ret = kmem_cache_alloc_bulk(cache, GFP_KERNEL, p_size, (void **)&p);
> +       if (!ret) {
> +               kunit_err(test, "Allocation failed: %s\n", __func__);
> +               kmem_cache_destroy(cache);
> +               return;
> +       }
> +
> +       for (i = 0; i < p_size; i++)
> +               p[i][0] = p[i][size - 1] = 42;
> +
> +       kmem_cache_free_bulk(cache, p_size, (void **)&p);
> +       kmem_cache_destroy(cache);
> +}
> +
>  static char global_array[10];
>
>  static void kasan_global_oob(struct kunit *test)
> @@ -961,7 +989,8 @@ static struct kunit_case kasan_kunit_test_cases[] = {
>         KUNIT_CASE(kfree_via_page),
>         KUNIT_CASE(kfree_via_phys),
>         KUNIT_CASE(kmem_cache_oob),
> -       KUNIT_CASE(memcg_accounted_kmem_cache),
> +       KUNIT_CASE(kmem_cache_accounted),
> +       KUNIT_CASE(kmem_cache_bulk),
>         KUNIT_CASE(kasan_global_oob),
>         KUNIT_CASE(kasan_stack_oob),
>         KUNIT_CASE(kasan_alloca_oob_left),
> --
> 2.30.0.284.gd98b1dd5eaa7-goog
>