From 5a3cf86978a1ac433407704ec280919751aa2699 Mon Sep 17 00:00:00 2001 From: Josh Poimboeuf Date: Tue, 11 Jul 2017 10:33:41 -0500 Subject: [PATCH] x86/dumpstack: Fix interrupt and exception stack boundary checks On x86_64, the double fault exception stack is located immediately after the interrupt stack in memory. This causes confusion in the unwinder when it tries to unwind through an empty interrupt stack, where the stack pointer points to the address bordering the two stacks. The unwinder incorrectly thinks it's running on the double fault stack. Fix this kind of stack border confusion by never considering the beginning address of an exception or interrupt stack to be part of the stack. Signed-off-by: Josh Poimboeuf Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Jiri Slaby Cc: Linus Torvalds Cc: Mike Galbraith Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: live-patching@vger.kernel.org Fixes: 5fe599e02e41 ("x86/dumpstack: Add support for unwinding empty IRQ stacks") Link: http://lkml.kernel.org/r/bcc142160a5104de5c354c21c394c93a0173943f.1499786555.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar --- arch/x86/kernel/dumpstack_32.c | 4 ++-- arch/x86/kernel/dumpstack_64.c | 4 ++-- 2 files changed, 4 insertions(+), 4 deletions(-) diff --git a/arch/x86/kernel/dumpstack_32.c b/arch/x86/kernel/dumpstack_32.c index e5f0b40e66d2..4f0481474903 100644 --- a/arch/x86/kernel/dumpstack_32.c +++ b/arch/x86/kernel/dumpstack_32.c @@ -37,7 +37,7 @@ static bool in_hardirq_stack(unsigned long *stack, struct stack_info *info) * This is a software stack, so 'end' can be a valid stack pointer. * It just means the stack is empty. */ - if (stack < begin || stack > end) + if (stack <= begin || stack > end) return false; info->type = STACK_TYPE_IRQ; @@ -62,7 +62,7 @@ static bool in_softirq_stack(unsigned long *stack, struct stack_info *info) * This is a software stack, so 'end' can be a valid stack pointer. * It just means the stack is empty. */ - if (stack < begin || stack > end) + if (stack <= begin || stack > end) return false; info->type = STACK_TYPE_SOFTIRQ; diff --git a/arch/x86/kernel/dumpstack_64.c b/arch/x86/kernel/dumpstack_64.c index 3e1471d57487..225af4184f06 100644 --- a/arch/x86/kernel/dumpstack_64.c +++ b/arch/x86/kernel/dumpstack_64.c @@ -55,7 +55,7 @@ static bool in_exception_stack(unsigned long *stack, struct stack_info *info) begin = end - (exception_stack_sizes[k] / sizeof(long)); regs = (struct pt_regs *)end - 1; - if (stack < begin || stack >= end) + if (stack <= begin || stack >= end) continue; info->type = STACK_TYPE_EXCEPTION + k; @@ -78,7 +78,7 @@ static bool in_irq_stack(unsigned long *stack, struct stack_info *info) * This is a software stack, so 'end' can be a valid stack pointer. * It just means the stack is empty. */ - if (stack < begin || stack > end) + if (stack <= begin || stack > end) return false; info->type = STACK_TYPE_IRQ; -- 2.20.1