From 5c79d2a517a9905599d192db8ce77ab5f1a2faca Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Wed, 11 Feb 2009 16:31:00 +0900 Subject: x86: fix x86_32 stack protector bugs Impact: fix x86_32 stack protector Brian Gerst found out that %gs was being initialized to stack_canary instead of stack_canary - 20, which basically gave the same canary value for all threads. Fixing this also exposed the following bugs. * cpu_idle() didn't call boot_init_stack_canary() * stack canary switching in switch_to() was being done too late making the initial run of a new thread use the old stack canary value. Fix all of them and while at it update comment in cpu_idle() about calling boot_init_stack_canary(). Reported-by: Brian Gerst Signed-off-by: Tejun Heo Signed-off-by: Ingo Molnar --- arch/x86/kernel/process_64.c | 11 +++++------ 1 file changed, 5 insertions(+), 6 deletions(-) (limited to 'arch/x86/kernel/process_64.c') diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c index 8eb169e4558..836ef6575f0 100644 --- a/arch/x86/kernel/process_64.c +++ b/arch/x86/kernel/process_64.c @@ -120,12 +120,11 @@ void cpu_idle(void) current_thread_info()->status |= TS_POLLING; /* - * 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): + * If we're the non-boot CPU, nothing set the stack canary up + * for us. CPU0 already has it initialized but no harm in + * doing it again. 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). */ boot_init_stack_canary(); -- cgit v1.2.3-70-g09d2