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/include/asm/stackprotector.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'arch/x86/include/asm/stackprotector.h') diff --git a/arch/x86/include/asm/stackprotector.h b/arch/x86/include/asm/stackprotector.h index fa7e5bd6fbe..c2d742c6e15 100644 --- a/arch/x86/include/asm/stackprotector.h +++ b/arch/x86/include/asm/stackprotector.h @@ -85,7 +85,7 @@ static __always_inline void boot_init_stack_canary(void) static inline void setup_stack_canary_segment(int cpu) { #ifdef CONFIG_X86_32 - unsigned long canary = (unsigned long)&per_cpu(stack_canary, cpu); + unsigned long canary = (unsigned long)&per_cpu(stack_canary, cpu) - 20; struct desc_struct *gdt_table = get_cpu_gdt_table(cpu); struct desc_struct desc; -- cgit v1.2.3-70-g09d2