Re: [PATCH 2/5] fork,random: use get_random_canary to set tsk->stack_canary

From	Kees Cook <keescook@google.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH 2/5] fork,random: use get_random_canary to set tsk->stack_canary
Date	2017-05-24 18:20 +0200
Message-ID	<tKHaV-4zP-5@gated-at.bofh.it> (permalink)
References	<tKGRz-4dh-7@gated-at.bofh.it> <tKGRA-4dh-25@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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On Wed, May 24, 2017 at 8:57 AM,  <riel@redhat.com> wrote:
> From: Rik van Riel <riel@redhat.com>
>
> Use the ascii-armor canary to prevent unterminated C string overflows
> from being able to successfully overwrite the canary, even if they
> somehow obtain the canary value.
>
> Inspired by execshield ascii-armor and Daniel Micay's linux-hardened tree.
>
> Signed-off-by: Rik van Riel <riel@redhat.com>

Acked-by: Kees Cook <keescook@chromium.org>

-Kees

> ---
>  kernel/fork.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/kernel/fork.c b/kernel/fork.c
> index aa1076c5e4a9..b3591e9250a8 100644
> --- a/kernel/fork.c
> +++ b/kernel/fork.c
> @@ -560,7 +560,7 @@ static struct task_struct *dup_task_struct(struct task_struct *orig, int node)
>         set_task_stack_end_magic(tsk);
>
>  #ifdef CONFIG_CC_STACKPROTECTOR
> -       tsk->stack_canary = get_random_long();
> +       tsk->stack_canary = get_random_canary();
>  #endif
>
>         /*
> --
> 2.9.3
>



-- 
Kees Cook
Pixel Security

Thread

[PATCH v2 0/5] stackprotector: ascii armor the stack canary riel@redhat.com - 2017-05-24 18:00 +0200
  [PATCH 1/5] random,stackprotect: introduce get_random_canary function riel@redhat.com - 2017-05-24 18:00 +0200
    Re: [PATCH 1/5] random,stackprotect: introduce get_random_canary function Kees Cook <keescook@google.com> - 2017-05-24 18:20 +0200
  [PATCH 4/5] arm64: ascii armor the arm64 boot init stack canary riel@redhat.com - 2017-05-24 18:00 +0200
    Re: [PATCH 4/5] arm64: ascii armor the arm64 boot init stack canary Kees Cook <keescook@google.com> - 2017-05-24 18:20 +0200
  [PATCH 3/5] x86: ascii armor the x86_64 boot init stack canary riel@redhat.com - 2017-05-24 18:00 +0200
    Re: [PATCH 3/5] x86: ascii armor the x86_64 boot init stack canary Kees Cook <keescook@google.com> - 2017-05-24 18:20 +0200
  [PATCH 2/5] fork,random: use get_random_canary to set tsk->stack_canary riel@redhat.com - 2017-05-24 18:00 +0200
    Re: [PATCH 2/5] fork,random: use get_random_canary to set tsk->stack_canary Kees Cook <keescook@google.com> - 2017-05-24 18:20 +0200
  [PATCH 5/5] sh64: ascii armor the sh64 boot init stack canary Rik van Riel <riel@redhat.com> - 2017-05-24 18:40 +0200
    Re: [PATCH 5/5] sh64: ascii armor the sh64 boot init stack canary Kees Cook <keescook@google.com> - 2017-05-24 18:40 +0200
  [PATCH 5/5] sh64: ascii armor the sh64 boot init stack canary riel@redhat.com - 2017-05-24 18:50 +0200

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