x86/dumpstack: Fix off-by-one errors in stack identification

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 an overflowed
IRQ or IST stack from being dumped properly.

[ tglx: Do the same for 32-bit ]

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Sean Christopherson <sean.j.christopherson@intel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: x86-ml <x86@kernel.org>
Link: https://lkml.kernel.org/r/20190414160143.785651055@linutronix.de

2 files changed, 4 insertions, 4 deletions

diff --git a/arch/x86/kernel/dumpstack_32.c b/arch/x86/kernel/dumpstack_32.c
index cd53f3030e40..d305440ebe9c 100644
--- a/arch/x86/kernel/dumpstack_32.c
+++ b/arch/x86/kernel/dumpstack_32.c
@@ -41,7 +41,7 @@ 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;
@@ -66,7 +66,7 @@ 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 5cdb9e84da57..90f0fa88cbb3 100644
--- a/arch/x86/kernel/dumpstack_64.c
+++ b/arch/x86/kernel/dumpstack_64.c
@@ -65,7 +65,7 @@ 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;
@@ -88,7 +88,7 @@ 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;