Le 19/09/2018 à 13:58, Peter Zijlstra a écrit :
On Wed, Sep 19, 2018 at 11:14:43AM +0000, Christophe Leroy wrote:
In order to allow the use of non global stack protector canary,
the stack canary needs to be located at a know offset defined
in Makefile via -mstack-protector-guard-offset.
On powerpc/32, register r2 points to current task_struct at
all time, the stack_canary located inside task_struct can be
used directly if it is located in a known place.
In order to allow that, this patch moves the stack_canary field
out of the randomized area of task_struct.
And you cannot use something like asm-offsets to extract this?
I have not been able to find a way to define the compilation flags AFTER
building asm-offsets.h, see https://patchwork.ozlabs.org/patch/971521/
If you have a suggestion, it is welcomed.
Signed-off-by: Christophe Leroy <christophe.le...@c-s.fr>
---
include/linux/sched.h | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 977cb57d7bc9..1d977b8a4bac 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -601,6 +601,10 @@ struct task_struct {
/* -1 unrunnable, 0 runnable, >0 stopped: */
volatile long state;
+#ifdef CONFIG_STACKPROTECTOR
+ /* Canary value for the -fstack-protector GCC feature: */
+ unsigned long stack_canary;
+#endif
/*
* This begins the randomizable portion of task_struct. Only
* scheduling-critical items should be added above here.
Might as well put it before state, right after the task_info thing.
Yes, it doesn't make much difference, don't any arch expect state at
offset 0 ?
Christophe
