From 18aa8bb12dcb10adc3d7c9d69714d53667c0ab7f Mon Sep 17 00:00:00 2001 From: Ingo Molnar Date: Thu, 14 Feb 2008 09:42:02 +0100 Subject: stackprotector: add boot_init_stack_canary() add the boot_init_stack_canary() and make the secondary idle threads use it. Signed-off-by: Ingo Molnar Signed-off-by: Thomas Gleixner --- arch/x86/kernel/process_64.c | 6 ++---- include/asm-x86/stackprotector.h | 20 ++++++++++++++++++++ include/linux/stackprotector.h | 4 ++++ 3 files changed, 26 insertions(+), 4 deletions(-) diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c index d4c7ac7aa43..5107cb214c7 100644 --- a/arch/x86/kernel/process_64.c +++ b/arch/x86/kernel/process_64.c @@ -147,7 +147,6 @@ void cpu_idle(void) { current_thread_info()->status |= TS_POLLING; -#ifdef CONFIG_CC_STACKPROTECTOR /* * If we're the non-boot CPU, nothing set the PDA stack * canary up for us - and if we are the boot CPU we have @@ -156,9 +155,8 @@ void cpu_idle(void) * invalid canaries already on the stack wont ever * trigger): */ - current->stack_canary = get_random_int(); - write_pda(stack_canary, current->stack_canary); -#endif + boot_init_stack_canary(); + /* endless idle loop with no priority at all */ while (1) { tick_nohz_stop_sched_tick(); diff --git a/include/asm-x86/stackprotector.h b/include/asm-x86/stackprotector.h index dcac7a6bdba..0f91f7a2688 100644 --- a/include/asm-x86/stackprotector.h +++ b/include/asm-x86/stackprotector.h @@ -1,4 +1,24 @@ #ifndef _ASM_STACKPROTECTOR_H #define _ASM_STACKPROTECTOR_H 1 +/* + * Initialize the stackprotector canary value. + * + * NOTE: this must only be called from functions that never return, + * and it must always be inlined. + */ +static __always_inline void boot_init_stack_canary(void) +{ + /* + * If we're the non-boot CPU, nothing set the PDA stack + * canary up for us - and if we are the boot CPU we have + * a 0 stack canary. This is a good place for updating + * it, as we wont ever return from this function (so the + * invalid canaries already on the stack wont ever + * trigger): + */ + current->stack_canary = get_random_int(); + write_pda(stack_canary, current->stack_canary); +} + #endif diff --git a/include/linux/stackprotector.h b/include/linux/stackprotector.h index d3e8bbe602f..422e71aafd0 100644 --- a/include/linux/stackprotector.h +++ b/include/linux/stackprotector.h @@ -3,6 +3,10 @@ #ifdef CONFIG_CC_STACKPROTECTOR # include +#else +static inline void boot_init_stack_canary(void) +{ +} #endif #endif -- cgit v1.2.3-70-g09d2