[PATCH 2/2] kasan: add test for invalid size in memmove

[PATCH 2/2] kasan: add test for invalid size in memmove

[Walter Wu]

Test size is negative numbers in memmove in order to verify
whether it correctly get KASAN report.

Signed-off-by: Walter Wu <walter-zh.wu@mediatek.com>
---
 lib/test_kasan.c | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/lib/test_kasan.c b/lib/test_kasan.c
index 49cc4d570a40..06942cf585cc 100644
--- a/lib/test_kasan.c
+++ b/lib/test_kasan.c
@@ -283,6 +283,23 @@ static noinline void __init kmalloc_oob_in_memset(void)
 	kfree(ptr);
 }
 
+static noinline void __init kmalloc_memmove_invalid_size(void)
+{
+	char *ptr;
+	size_t size = 64;
+
+	pr_info("invalid size in memmove\n");
+	ptr = kmalloc(size, GFP_KERNEL);
+	if (!ptr) {
+		pr_err("Allocation failed\n");
+		return;
+	}
+
+	memset((char *)ptr, 0, 64);
+	memmove((char *)ptr, (char *)ptr + 4, -2);
+	kfree(ptr);
+}
+
 static noinline void __init kmalloc_uaf(void)
 {
 	char *ptr;
@@ -773,6 +790,7 @@ static int __init kmalloc_tests_init(void)
 	kmalloc_oob_memset_4();
 	kmalloc_oob_memset_8();
 	kmalloc_oob_memset_16();
+	kmalloc_memmove_invalid_size();
 	kmalloc_uaf();
 	kmalloc_uaf_memset();
 	kmalloc_uaf2();
-- 
2.18.0

Re: [PATCH 2/2] kasan: add test for invalid size in memmove

[Dmitry Vyukov]

On Mon, Oct 14, 2019 at 12:37 PM Walter Wu <walter-zh.wu@mediatek.com> wrote:
>
> Test size is negative numbers in memmove in order to verify
> whether it correctly get KASAN report.
>
> Signed-off-by: Walter Wu <walter-zh.wu@mediatek.com>

Reviewed-by: Dmitry Vyukov <dvyukov@google.com>

Thanks!

> ---
>  lib/test_kasan.c | 18 ++++++++++++++++++
>  1 file changed, 18 insertions(+)
>
> diff --git a/lib/test_kasan.c b/lib/test_kasan.c
> index 49cc4d570a40..06942cf585cc 100644
> --- a/lib/test_kasan.c
> +++ b/lib/test_kasan.c
> @@ -283,6 +283,23 @@ static noinline void __init kmalloc_oob_in_memset(void)
>         kfree(ptr);
>  }
>
> +static noinline void __init kmalloc_memmove_invalid_size(void)
> +{
> +       char *ptr;
> +       size_t size = 64;
> +
> +       pr_info("invalid size in memmove\n");
> +       ptr = kmalloc(size, GFP_KERNEL);
> +       if (!ptr) {
> +               pr_err("Allocation failed\n");
> +               return;
> +       }
> +
> +       memset((char *)ptr, 0, 64);
> +       memmove((char *)ptr, (char *)ptr + 4, -2);
> +       kfree(ptr);
> +}
> +
>  static noinline void __init kmalloc_uaf(void)
>  {
>         char *ptr;
> @@ -773,6 +790,7 @@ static int __init kmalloc_tests_init(void)
>         kmalloc_oob_memset_4();
>         kmalloc_oob_memset_8();
>         kmalloc_oob_memset_16();
> +       kmalloc_memmove_invalid_size();
>         kmalloc_uaf();
>         kmalloc_uaf_memset();
>         kmalloc_uaf2();
> --
> 2.18.0
>
> --
> You received this message because you are subscribed to the Google Groups "kasan-dev" group.
> To unsubscribe from this group and stop receiving emails from it, send an email to kasan-dev+unsubscribe@googlegroups.com.
> To view this discussion on the web visit https://groups.google.com/d/msgid/kasan-dev/20191014103654.17982-1-walter-zh.wu%40mediatek.com.

Re: [PATCH 2/2] kasan: add test for invalid size in memmove

[Matthew Wilcox]

On Mon, Oct 14, 2019 at 06:36:54PM +0800, Walter Wu wrote:
> Test size is negative numbers in memmove in order to verify
> whether it correctly get KASAN report.

You're not testing negative numbers, though.  memmove() takes an unsigned
type, so you're testing a very large number.

Re: [PATCH 2/2] kasan: add test for invalid size in memmove

[Walter Wu]

On Mon, 2019-10-14 at 08:07 -0700, Matthew Wilcox wrote:
> On Mon, Oct 14, 2019 at 06:36:54PM +0800, Walter Wu wrote:
> > Test size is negative numbers in memmove in order to verify
> > whether it correctly get KASAN report.
> 
> You're not testing negative numbers, though.  memmove() takes an unsigned
> type, so you're testing a very large number.
> 
Casting negative numbers to size_t would indeed turn up as a "large"
size_t and its value will be larger than ULONG_MAX/2. We mainly want to
express this case. Maybe we can add some descriptions. Thanks for your
reminder.