linux-kernel - Re: [PATCH] kasan: add test for -fsanitize-address-use-after-scope

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Date:   Mon, 5 Dec 2016 15:20:07 +0100
From:   Dmitry Vyukov <dvyukov@...gle.com>
To:     Jiri Slaby <jslaby@...e.cz>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        LKML <linux-kernel@...r.kernel.org>, marxin <mliska@...e.cz>
Subject: Re: [PATCH] kasan: add test for -fsanitize-address-use-after-scope

On Mon, Dec 5, 2016 at 3:16 PM, Jiri Slaby <jslaby@...e.cz> wrote:
> From: marxin <mliska@...e.cz>
>
> In commit 828347f8f9a5 ("kasan: support use-after-scope detection") we
> added support for use-after-scope. Let's add a check if it actually
> works.
>
> Signed-off-by: Martin Liska <mliska@...e.cz>
> Signed-off-by: Jiri Slaby <jslaby@...e.cz>
> ---
>  lib/test_kasan.c | 14 ++++++++++++++
>  1 file changed, 14 insertions(+)
>
> diff --git a/lib/test_kasan.c b/lib/test_kasan.c
> index fbdf87920093..32f31b8d306e 100644
> --- a/lib/test_kasan.c
> +++ b/lib/test_kasan.c
> @@ -352,6 +352,19 @@ static noinline void __init kasan_stack_oob(void)
>         *(volatile char *)p;
>  }
>
> +static noinline void __init kasan_stack_use_after_scope(void)
> +{
> +       char *ptr = NULL;
> +       {
> +               char a;
> +
> +               ptr = &a;
> +       }
> +
> +       pr_info("use-after-scope on stack\n");
> +       *(volatile char *)ptr;
> +}
> +
>  static noinline void __init ksize_unpoisons_memory(void)
>  {
>         char *ptr;
> @@ -461,6 +474,7 @@ static int __init kmalloc_tests_init(void)
>         kmalloc_uaf2();
>         kmem_cache_oob();
>         kasan_stack_oob();
> +       kasan_stack_use_after_scope();
>         kasan_global_oob();
>         ksize_unpoisons_memory();
>         copy_user_test();
> --
> 2.11.0


I might be missing something, but my patch contained a test:

+static noinline void __init use_after_scope_test(void)
+{
+       volatile char *volatile p;
+
+       pr_info("use-after-scope on int\n");
+       {
+               int local = 0;
+
+               p = (char *)&local;
+       }
+       p[0] = 1;
+       p[3] = 1;
+
+       pr_info("use-after-scope on array\n");
+       {
+               char local[1024] = {0};
+
+               p = local;
+       }
+       p[0] = 1;
+       p[1023] = 1;
+}
+