diff mbox

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

Message ID 20170524155751.424-3-riel@redhat.com (mailing list archive)
State New, archived
Headers show

Commit Message

Rik van Riel May 24, 2017, 3:57 p.m. UTC 
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>
---
 kernel/fork.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Kees Cook May 24, 2017, 4:16 p.m. UTC | #1 
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
>
diff mbox

Patch

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
 
 	/*