From: Kees Cook <keescook@chromium•org>
To: Andrey Konovalov <andreyknvl@gmail•com>
Cc: Christoph Lameter <cl@linux•com>,
Dmitry Vyukov <dvyukov@google•com>,
Jakub Kicinski <kuba@kernel•org>, Paolo Abeni <pabeni@redhat•com>,
Pekka Enberg <penberg@kernel•org>,
David Rientjes <rientjes@google•com>,
Joonsoo Kim <iamjoonsoo.kim@lge•com>,
Andrew Morton <akpm@linux-foundation•org>,
Vlastimil Babka <vbabka@suse•cz>,
Roman Gushchin <roman.gushchin@linux•dev>,
Hyeonggon Yoo <42.hyeyoo@gmail•com>,
Andrey Ryabinin <ryabinin.a.a@gmail•com>,
Alexander Potapenko <glider@google•com>,
Vincenzo Frascino <vincenzo.frascino@arm•com>,
linux-mm@kvack•org, kasan-dev@googlegroups•com,
netdev@vger•kernel.org, linux-kernel@vger•kernel.org,
linux-hardening@vger•kernel.org
Subject: Re: [PATCH] mm: Make ksize() a reporting-only function
Date: Thu, 27 Oct 2022 12:13:20 -0700 [thread overview]
Message-ID: <202210271212.EB69EF1@keescook> (raw)
In-Reply-To: <CA+fCnZcj_Hq1NQv1L2U7+A8quqj+4kA=8A7LwOWz5eYNQFra+A@mail.gmail.com>
On Thu, Oct 27, 2022 at 09:05:45PM +0200, Andrey Konovalov wrote:
> On Sat, Oct 22, 2022 at 8:08 PM Kees Cook <keescook@chromium•org> wrote:
> [...]
> > -/* Check that ksize() makes the whole object accessible. */
> > +/* Check that ksize() does NOT unpoison whole object. */
> > static void ksize_unpoisons_memory(struct kunit *test)
> > {
> > char *ptr;
> > @@ -791,15 +791,17 @@ static void ksize_unpoisons_memory(struct kunit *test)
> >
> > ptr = kmalloc(size, GFP_KERNEL);
> > KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr);
> > +
> > real_size = ksize(ptr);
> > + KUNIT_EXPECT_GT(test, real_size, size);
> >
> > OPTIMIZER_HIDE_VAR(ptr);
> >
> > /* This access shouldn't trigger a KASAN report. */
> > - ptr[size] = 'x';
> > + ptr[size - 1] = 'x';
> >
> > /* This one must. */
> > - KUNIT_EXPECT_KASAN_FAIL(test, ((volatile char *)ptr)[real_size]);
> > + KUNIT_EXPECT_KASAN_FAIL(test, ((volatile char *)ptr)[real_size - 1]);
>
> How about also accessing ptr[size] here? It would allow for a more
> precise checking of the in-object redzone.
Sure! Probably both ptr[size] and ptr[real_size -1], yes?
--
Kees Cook
next prev parent reply other threads:[~2022-10-27 19:13 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-10-22 18:08 [PATCH] mm: Make ksize() a reporting-only function Kees Cook
2022-10-24 6:13 ` kernel test robot
2022-10-25 11:53 ` Vlastimil Babka
2022-10-25 18:38 ` Kees Cook
2022-10-27 19:05 ` Andrey Konovalov
2022-10-27 19:13 ` Kees Cook [this message]
2022-10-27 19:15 ` Andrey Konovalov
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