diff mbox series

[8/8] kasan: test: avoid corrupting memory in kasan_rcu_uaf

Message ID da8d30df9206b54be2768b27bb026ec06e4da7a4.1628709663.git.andreyknvl@gmail.com (mailing list archive)
State New
Headers show
Series kasan: test: avoid crashing the kernel with HW_TAGS | expand

Commit Message

andrey.konovalov@linux.dev Aug. 11, 2021, 7:34 p.m. UTC 
From: Andrey Konovalov <andreyknvl@gmail.com>

kasan_rcu_uaf() writes to freed memory via kasan_rcu_reclaim(), which is
only safe with the GENERIC mode (as it uses quarantine). For other modes,
this test corrupts kernel memory, which might result in a crash.

Turn the write into a read.

Signed-off-by: Andrey Konovalov <andreyknvl@gmail.com>
---
 lib/test_kasan_module.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Marco Elver Aug. 12, 2021, 8:50 a.m. UTC | #1 
On Wed, 11 Aug 2021 at 21:34, <andrey.konovalov@linux.dev> wrote:
>
> From: Andrey Konovalov <andreyknvl@gmail.com>
>
> kasan_rcu_uaf() writes to freed memory via kasan_rcu_reclaim(), which is
> only safe with the GENERIC mode (as it uses quarantine). For other modes,
> this test corrupts kernel memory, which might result in a crash.
>
> Turn the write into a read.
>
> Signed-off-by: Andrey Konovalov <andreyknvl@gmail.com>

Reviewed-by: Marco Elver <elver@google.com>


> ---
>  lib/test_kasan_module.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/lib/test_kasan_module.c b/lib/test_kasan_module.c
> index fa73b9df0be4..7ebf433edef3 100644
> --- a/lib/test_kasan_module.c
> +++ b/lib/test_kasan_module.c
> @@ -71,7 +71,7 @@ static noinline void __init kasan_rcu_reclaim(struct rcu_head *rp)
>                                                 struct kasan_rcu_info, rcu);
>
>         kfree(fp);
> -       fp->i = 1;
> +       ((volatile struct kasan_rcu_info *)fp)->i;
>  }
>
>  static noinline void __init kasan_rcu_uaf(void)
> --
> 2.25.1
>
diff mbox series

Patch

diff --git a/lib/test_kasan_module.c b/lib/test_kasan_module.c
index fa73b9df0be4..7ebf433edef3 100644
--- a/lib/test_kasan_module.c
+++ b/lib/test_kasan_module.c
@@ -71,7 +71,7 @@  static noinline void __init kasan_rcu_reclaim(struct rcu_head *rp)
 						struct kasan_rcu_info, rcu);
 
 	kfree(fp);
-	fp->i = 1;
+	((volatile struct kasan_rcu_info *)fp)->i;
 }
 
 static noinline void __init kasan_rcu_uaf(void)