linux-kernel - [patch V2 02/29] x86/dumpstack: Fix off-by-one errors in stack identification

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Message-Id: <20190405150928.596372581@linutronix.de>
Date:   Fri, 05 Apr 2019 17:07:00 +0200
From:   Thomas Gleixner <tglx@...utronix.de>
To:     LKML <linux-kernel@...r.kernel.org>
Cc:     x86@...nel.org, Andy Lutomirski <luto@...nel.org>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        Sean Christopherson <sean.j.christopherson@...el.com>
Subject: [patch V2 02/29] x86/dumpstack: Fix off-by-one errors in stack
 identification

From: Andy Lutomirski <luto@...nel.org>

The get_stack_info() function is off-by-one when checking whether an
address is on a IRQ stack or a IST stack.  This prevents a overflowed IRQ
or IST stack from being dumped properly.

[ tglx: Do the same for 32-bit ]

Signed-off-by: Andy Lutomirski <luto@...nel.org>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Cc: Josh Poimboeuf <jpoimboe@...hat.com>

---
 arch/x86/kernel/dumpstack_32.c |    4 ++--
 arch/x86/kernel/dumpstack_64.c |    4 ++--
 2 files changed, 4 insertions(+), 4 deletions(-)

--- a/arch/x86/kernel/dumpstack_32.c
+++ b/arch/x86/kernel/dumpstack_32.c
@@ -41,7 +41,7 @@ static bool in_hardirq_stack(unsigned lo
 	 * 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;
@@ -66,7 +66,7 @@ static bool in_softirq_stack(unsigned lo
 	 * 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;
--- a/arch/x86/kernel/dumpstack_64.c
+++ b/arch/x86/kernel/dumpstack_64.c
@@ -65,7 +65,7 @@ static bool in_exception_stack(unsigned
 		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;
@@ -88,7 +88,7 @@ static bool in_irq_stack(unsigned long *
 	 * 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;