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

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Date:   Thu, 14 Jan 2021 16:32:53 +0100
From:   Andrey Konovalov <andreyknvl@...gle.com>
To:     Marco Elver <elver@...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, Jan 13, 2021 at 5:38 PM Marco Elver <elver@...gle.com> wrote:
>
> 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
> >

Will fix all in v3, thanks!