[PATCH] x86/xen: Fix some null pointer dereference issues in smp.c

[Kunwu Chan <chentao@xxxxxxxxxx>]

kasprintf() returns a pointer to dynamically allocated memory
which can be NULL upon failure. Ensure the allocation was successful
by checking the pointer validity.

Signed-off-by: Kunwu Chan <chentao@xxxxxxxxxx>
---
 arch/x86/xen/smp.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/arch/x86/xen/smp.c b/arch/x86/xen/smp.c
index 4b0d6fff88de..f27608ed80a0 100644
--- a/arch/x86/xen/smp.c
+++ b/arch/x86/xen/smp.c
@@ -65,6 +65,8 @@ int xen_smp_intr_init(unsigned int cpu)
        char *resched_name, *callfunc_name, *debug_name;
 
        resched_name = kasprintf(GFP_KERNEL, "resched%d", cpu);
+       if (!resched_name)
+               goto fail;
        per_cpu(xen_resched_irq, cpu).name = resched_name;
        rc = bind_ipi_to_irqhandler(XEN_RESCHEDULE_VECTOR,
                                    cpu,
@@ -77,6 +79,8 @@ int xen_smp_intr_init(unsigned int cpu)
        per_cpu(xen_resched_irq, cpu).irq = rc;
 
        callfunc_name = kasprintf(GFP_KERNEL, "callfunc%d", cpu);
+       if (!callfunc_name)
+               goto fail;
        per_cpu(xen_callfunc_irq, cpu).name = callfunc_name;
        rc = bind_ipi_to_irqhandler(XEN_CALL_FUNCTION_VECTOR,
                                    cpu,
@@ -90,6 +94,8 @@ int xen_smp_intr_init(unsigned int cpu)
 
        if (!xen_fifo_events) {
                debug_name = kasprintf(GFP_KERNEL, "debug%d", cpu);
+               if (!debug_name)
+                       goto fail;
                per_cpu(xen_debug_irq, cpu).name = debug_name;
                rc = bind_virq_to_irqhandler(VIRQ_DEBUG, cpu,
                                             xen_debug_interrupt,
@@ -101,6 +107,8 @@ int xen_smp_intr_init(unsigned int cpu)
        }
 
        callfunc_name = kasprintf(GFP_KERNEL, "callfuncsingle%d", cpu);
+       if (!callfunc_name)
+               goto fail;
        per_cpu(xen_callfuncsingle_irq, cpu).name = callfunc_name;
        rc = bind_ipi_to_irqhandler(XEN_CALL_FUNCTION_SINGLE_VECTOR,
                                    cpu,
-- 
2.39.2