2019-10-14 10:38:30

by Walter Wu

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

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

Signed-off-by: Walter Wu <[email protected]>
---
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

2019-10-14 10:45:05

by Dmitry Vyukov

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

On Mon, Oct 14, 2019 at 12:37 PM Walter Wu <[email protected]> wrote:
>
> Test size is negative numbers in memmove in order to verify
> whether it correctly get KASAN report.
>
> Signed-off-by: Walter Wu <[email protected]>

Reviewed-by: Dmitry Vyukov <[email protected]>

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
>
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2019-10-14 15:09:54

by Matthew Wilcox

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

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.

2019-10-14 16:31:14

by Walter Wu

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

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.