Re: [PATCH 08/11] kasan: adopt kmalloc_uaf2 test to HW_TAGS mode

[Andrey Konovalov <andreyknvl@xxxxxxxxxx>]

On Tue, Jan 12, 2021 at 9:26 AM Alexander Potapenko <glider@xxxxxxxxxx> wrote:
>
> Nit: s/adopt/adapt in the title.
>
>
> > +again:
> >         ptr1 = kmalloc(size, GFP_KERNEL);
> >         KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr1);
> >
> > @@ -384,6 +386,13 @@ static void kmalloc_uaf2(struct kunit *test)
> >         ptr2 = kmalloc(size, GFP_KERNEL);
> >         KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr2);
> >
> > +       /*
> > +        * For tag-based KASAN ptr1 and ptr2 tags might happen to be the same.
> > +        * Allow up to 4 attempts at generating different tags.
> > +        */
> > +       if (!IS_ENABLED(CONFIG_KASAN_GENERIC) && ptr1 == ptr2 && counter++ < 4)
> > +               goto again;
> > +
>
> Looks like we are leaking memory allocated for ptr2 here?

Will fix in v2, thanks!