[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...@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

[Dmitry Vyukov]

On Mon, Oct 14, 2019 at 12:37 PM Walter Wu <walter...@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...@mediatek.com>

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

Thanks!

> --
> 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+...@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.

[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.

[Walter Wu]

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.

[Walter Wu]

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

Casting negative numbers to size_t would indeed turn up as a 'large'
size_t, so it will have out-of-bounds bug and detected by KASAN.

Changes in v2:
Add some descriptions for clarity the testcase.

Signed-off-by: Walter Wu <walter...@mediatek.com>
Reviewed-by: Dmitry Vyukov <dvy...@google.com>