linux-kernel - Re: [PATCH v3 14/15] kasan: add a test for kmem_cache_alloc/free

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Date:   Fri, 15 Jan 2021 14:16:26 +0100
From:   Marco Elver <elver@...gle.com>
To:     Andrey Konovalov <andreyknvl@...gle.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Catalin Marinas <catalin.marinas@....com>,
        Vincenzo Frascino <vincenzo.frascino@....com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Alexander Potapenko <glider@...gle.com>,
        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@...glegroups.com, linux-arm-kernel@...ts.infradead.org,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 14/15] kasan: add a test for kmem_cache_alloc/free_bulk

On Thu, Jan 14, 2021 at 08:36PM +0100, Andrey Konovalov wrote:
> Add a test for kmem_cache_alloc/free_bulk to make sure there are no
> false-positives when these functions are used.
> 
> Link: https://linux-review.googlesource.com/id/I2a8bf797aecf81baeac61380c567308f319e263d
> Signed-off-by: Andrey Konovalov <andreyknvl@...gle.com>

Reviewed-by: Marco Elver <elver@...gle.com>

> ---
>  lib/test_kasan.c | 38 +++++++++++++++++++++++++++++++++-----
>  1 file changed, 33 insertions(+), 5 deletions(-)
> 
> diff --git a/lib/test_kasan.c b/lib/test_kasan.c
> index ab22a653762e..a96376aa7293 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 +524,31 @@ 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;
> +	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, ARRAY_SIZE(p), (void **)&p);
> +	if (!ret) {
> +		kunit_err(test, "Allocation failed: %s\n", __func__);
> +		kmem_cache_destroy(cache);
> +		return;
> +	}
> +
> +	for (i = 0; i < ARRAY_SIZE(p); i++)
> +		p[i][0] = p[i][size - 1] = 42;
> +
> +	kmem_cache_free_bulk(cache, ARRAY_SIZE(p), (void **)&p);
> +	kmem_cache_destroy(cache);
> +}
> +
>  static char global_array[10];
>  
>  static void kasan_global_oob(struct kunit *test)
> @@ -961,7 +988,8 @@ 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
>