Commit df835e70 authored by Thomas Gleixner's avatar Thomas Gleixner Committed by Borislav Petkov
Browse files

x86/irq/64: Sanitize the top/bottom confusion 



On x86, stacks go top to bottom, but the stack overflow check uses it
the other way round, which is just confusing. Clean it up and sanitize
the warning string a bit.

Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarBorislav Petkov <bp@suse.de>
Reviewed-by: default avatarSean Christopherson <sean.j.christopherson@intel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Nicolai Stange <nstange@suse.de>
Cc: x86-ml <x86@kernel.org>
Link: https://lkml.kernel.org/r/20190414160143.961241397@linutronix.de
parent 4f44b8f0

arch/x86/kernel/irq_64.c

+11 −11
Original line number Diff line number Diff line
@@ -42,7 +42,7 @@ int sysctl_panic_on_stackoverflow; 
static inline void stack_overflow_check(struct pt_regs *regs)

{

#ifdef CONFIG_DEBUG_STACKOVERFLOW

#define STACK_TOP_MARGIN	128

#define STACK_MARGIN	128

	struct orig_ist *oist;

	u64 irq_stack_top, irq_stack_bottom;

	u64 estack_top, estack_bottom;
@@ -51,25 +51,25 @@ static inline void stack_overflow_check(struct pt_regs *regs) 
	if (user_mode(regs))

		return;



	if (regs->sp >= curbase + sizeof(struct pt_regs) + STACK_TOP_MARGIN &&

	if (regs->sp >= curbase + sizeof(struct pt_regs) + STACK_MARGIN &&

	    regs->sp <= curbase + THREAD_SIZE)

		return;



	irq_stack_bottom = (u64)__this_cpu_read(irq_stack_ptr);

	irq_stack_top = irq_stack_bottom - IRQ_STACK_SIZE + STACK_TOP_MARGIN;

	if (regs->sp >= irq_stack_top && regs->sp <= irq_stack_bottom)

	irq_stack_top = (u64)__this_cpu_read(irq_stack_ptr);

	irq_stack_bottom = irq_stack_top - IRQ_STACK_SIZE + STACK_MARGIN;

	if (regs->sp >= irq_stack_bottom && regs->sp <= irq_stack_top)

		return;



	oist = this_cpu_ptr(&orig_ist);

	estack_bottom = (u64)oist->ist[DEBUG_STACK];

	estack_top = estack_bottom - DEBUG_STKSZ + STACK_TOP_MARGIN;

	if (regs->sp >= estack_top && regs->sp <= estack_bottom)

	estack_top = (u64)oist->ist[DEBUG_STACK];

	estack_bottom = estack_top - DEBUG_STKSZ + STACK_MARGIN;

	if (regs->sp >= estack_bottom && regs->sp <= estack_top)

		return;



	WARN_ONCE(1, "do_IRQ(): %s has overflown the kernel stack (cur:%Lx,sp:%lx,irq stk top-bottom:%Lx-%Lx,exception stk top-bottom:%Lx-%Lx,ip:%pF)\n",

	WARN_ONCE(1, "do_IRQ(): %s has overflown the kernel stack (cur:%Lx,sp:%lx, irq stack:%Lx-%Lx, exception stack: %Lx-%Lx, ip:%pF)\n",

		current->comm, curbase, regs->sp,

		irq_stack_top, irq_stack_bottom,

		estack_top, estack_bottom, (void *)regs->ip);

		irq_stack_bottom, irq_stack_top,

		estack_bottom, estack_top, (void *)regs->ip);



	if (sysctl_panic_on_stackoverflow)

		panic("low stack detected by irq handler - check messages\n");

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