From 467e6b7a7c0eb792ebaf322ddb7363742b4ead40 Mon Sep 17 00:00:00 2001 From: Mitsuo Hayasaka Date: Tue, 29 Nov 2011 15:08:45 +0900 Subject: [PATCH] x86: Clean up the range of stack overflow checking The overflow checking of kernel stack checks if the stack pointer points to the available kernel stack range, which is derived from the original overflow checking. It is clear that curbase address is always less than low boundary of available kernel stack. So, this patch removes the first condition that checks if the pointer is higher than curbase. Signed-off-by: Mitsuo Hayasaka Cc: yrl.pp-manager.tt@hitachi.com Cc: Randy Dunlap Link: http://lkml.kernel.org/r/20111129060845.11076.40916.stgit@ltc219.sdl.hitachi.co.jp Signed-off-by: Ingo Molnar Cc: "H. Peter Anvin" --- arch/x86/kernel/irq_64.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) diff --git a/arch/x86/kernel/irq_64.c b/arch/x86/kernel/irq_64.c index 42552b0..54e2b2b 100644 --- a/arch/x86/kernel/irq_64.c +++ b/arch/x86/kernel/irq_64.c @@ -46,10 +46,9 @@ static inline void stack_overflow_check(struct pt_regs *regs) if (user_mode_vm(regs)) return; - if (regs->sp >= curbase && - regs->sp <= curbase + THREAD_SIZE && - regs->sp >= curbase + sizeof(struct thread_info) + - sizeof(struct pt_regs) + 128) + if (regs->sp >= curbase + sizeof(struct thread_info) + + sizeof(struct pt_regs) + 128 && + regs->sp <= curbase + THREAD_SIZE) return; irq_stack_top = (u64)__get_cpu_var(irq_stack_union.irq_stack); -- 2.7.4