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x86/dumpstack: Fix interrupt and exception stack boundary checks

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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 <jpoimboe@redhat.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: live-patching@vger.kernel.org
Fixes: 5fe599e02e ("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 <mingo@kernel.org>
This commit is contained in:
Josh Poimboeuf 2017-07-11 10:33:41 -05:00 committed by Ingo Molnar
parent b0529beceb
commit 5a3cf86978
2 changed files with 4 additions and 4 deletions
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4
arch/x86/kernel/dumpstack_32.c
View file

@ -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;

4
arch/x86/kernel/dumpstack_64.c
View file

@ -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;