From: Kees Cook <keescook@chromium.org>
To: Marco Elver <elver@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Andrey Ryabinin <ryabinin.a.a@gmail.com>,
Alexander Potapenko <glider@google.com>,
Andrey Konovalov <andreyknvl@gmail.com>,
Dmitry Vyukov <dvyukov@google.com>,
kasan-dev@googlegroups.com, linux-kernel@vger.kernel.org,
linux-mm@kvack.org, Brendan Higgins <brendanhiggins@google.com>,
linux-hardening@vger.kernel.org, Nico Pache <npache@redhat.com>
Subject: Re: [PATCH] kasan: test: fix compatibility with FORTIFY_SOURCE
Date: Mon, 24 Jan 2022 10:24:34 -0800 [thread overview]
Message-ID: <202201241024.DA581869@keescook> (raw)
In-Reply-To: <20220124160744.1244685-1-elver@google.com>
On Mon, Jan 24, 2022 at 05:07:44PM +0100, Marco Elver wrote:
> With CONFIG_FORTIFY_SOURCE enabled, string functions will also perform
> dynamic checks using __builtin_object_size(ptr), which when failed will
> panic the kernel.
>
> Because the KASAN test deliberately performs out-of-bounds operations,
> the kernel panics with FORITY_SOURCE, for example:
>
> | kernel BUG at lib/string_helpers.c:910!
> | invalid opcode: 0000 [#1] PREEMPT SMP KASAN PTI
> | CPU: 1 PID: 137 Comm: kunit_try_catch Tainted: G B 5.16.0-rc3+ #3
> | Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.14.0-2 04/01/2014
> | RIP: 0010:fortify_panic+0x19/0x1b
> | ...
> | Call Trace:
> | <TASK>
> | kmalloc_oob_in_memset.cold+0x16/0x16
> | ...
>
> Fix it by also hiding `ptr` from the optimizer, which will ensure that
> __builtin_object_size() does not return a valid size, preventing
> fortified string functions from panicking.
>
> Reported-by: Nico Pache <npache@redhat.com>
> Signed-off-by: Marco Elver <elver@google.com>
Yup, more good fixes. Thanks!
Reviewed-by: Kees Cook <keescook@chromium.org>
--
Kees Cook
next prev parent reply other threads:[~2022-01-24 18:48 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-01-24 16:07 [PATCH] kasan: test: fix compatibility with FORTIFY_SOURCE Marco Elver
2022-01-24 17:54 ` Andrey Konovalov
2022-01-24 17:59 ` Marco Elver
2022-01-24 18:24 ` Kees Cook [this message]
2022-01-24 18:56 ` Nico Pache
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