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Groups > linux.kernel > #1649732

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

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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(-)

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

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[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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