[PATCH] use get_random_long for the per-task stack canary

[PATCH] use get_random_long for the per-task stack canary

[Daniel Micay]

The stack canary is an unsigned long and should be fully initialized to
random data rather than only 32 bits of random data.

Cc: stable@vger.kernel.org
Signed-off-by: Daniel Micay <danielmicay@gmail.com>
---
 kernel/fork.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/fork.c b/kernel/fork.c
index 56d85fd81411..ff84ff82f56a 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -537,7 +537,7 @@ 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_int();
+	tsk->stack_canary = get_random_long();
 #endif
 
 	/*
-- 
2.12.2

Re: [PATCH] use get_random_long for the per-task stack canary

[Arjan van de Ven]

On 5/4/2017 6:32 AM, Daniel Micay wrote:
> The stack canary is an unsigned long and should be fully initialized to
> random data rather than only 32 bits of random data.

that makes sense to me... ack

Re: [kernel-hardening] [PATCH] use get_random_long for the per-task stack canary

[Rik van Riel]

On Thu, 2017-05-04 at 09:32 -0400, Daniel Micay wrote:
> The stack canary is an unsigned long and should be fully initialized
> to
> random data rather than only 32 bits of random data.
> 
> Cc: stable@vger.kernel.org
> Signed-off-by: Daniel Micay <danielmicay@gmail.com>
> 
Acked-by: Rik van Riel <riel@redhat.com>

Re: [kernel-hardening] [PATCH] use get_random_long for the per-task stack canary

[Kees Cook]

On Thu, May 4, 2017 at 7:04 AM, Rik van Riel <riel@redhat.com> wrote:
> On Thu, 2017-05-04 at 09:32 -0400, Daniel Micay wrote:
>> The stack canary is an unsigned long and should be fully initialized
>> to
>> random data rather than only 32 bits of random data.
>>
>> Cc: stable@vger.kernel.org
>> Signed-off-by: Daniel Micay <danielmicay@gmail.com>
>>
> Acked-by: Rik van Riel <riel@redhat.com>

Thanks! Ingo, should this go via tip?

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

-Kees

-- 
Kees Cook
Pixel Security

[tip:core/urgent] stackprotector: Increase the per-task stack canary's random range from 32 bits to 64 bits on 64-bit platforms

[tip-bot for Daniel Micay]

Commit-ID:  5ea30e4e58040cfd6434c2f33dc3ea76e2c15b05
Gitweb:     http://git.kernel.org/tip/5ea30e4e58040cfd6434c2f33dc3ea76e2c15b05
Author:     Daniel Micay <danielmicay@gmail.com>
AuthorDate: Thu, 4 May 2017 09:32:09 -0400
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Fri, 5 May 2017 08:05:13 +0200

stackprotector: Increase the per-task stack canary's random range from 32 bits to 64 bits on 64-bit platforms

The stack canary is an 'unsigned long' and should be fully initialized to
random data rather than only 32 bits of random data.

Signed-off-by: Daniel Micay <danielmicay@gmail.com>
Acked-by: Arjan van de Ven <arjan@linux.intel.com>
Acked-by: Rik van Riel <riel@redhat.com>
Acked-by: Kees Cook <keescook@chromium.org>
Cc: Arjan van Ven <arjan@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: kernel-hardening@lists.openwall.com
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/20170504133209.3053-1-danielmicay@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 kernel/fork.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/fork.c b/kernel/fork.c
index 3a4343c..d681f8f 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -536,7 +536,7 @@ 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_int();
+	tsk->stack_canary = get_random_long();
 #endif
 
 	/*