[PATCH 4.9 140/164] stackprotector: Increase the per-task stack canarys random range from 32 bits to 64 bits on 64-bit platforms

[Greg Kroah-Hartman]

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Daniel Micay <danielmicay@xxxxxxxxx>

commit 5ea30e4e58040cfd6434c2f33dc3ea76e2c15b05 upstream.

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@xxxxxxxxx>
Acked-by: Arjan van de Ven <arjan@xxxxxxxxxxxxxxx>
Acked-by: Rik van Riel <riel@xxxxxxxxxx>
Acked-by: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: Arjan van Ven <arjan@xxxxxxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: kernel-hardening@xxxxxxxxxxxxxxxxxx
Link: http://lkml.kernel.org/r/20170504133209.3053-1-danielmicay@xxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 kernel/fork.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -521,7 +521,7 @@ static struct task_struct *dup_task_stru
 	set_task_stack_end_magic(tsk);
 
 #ifdef CONFIG_CC_STACKPROTECTOR
-	tsk->stack_canary = get_random_int();
+	tsk->stack_canary = get_random_long();
 #endif
 
 	/*