x86: Fix NULL pointer access in irq_force_complete_move() for Xen guests

commit bbd391a15d82e14efe9d69ba64cadb855b061dba upstream.

Upstream PV guests fail to boot because of a NULL pointer in
irq_force_complete_move().  It is possible that xen guests have
irq_desc->chip_data = NULL.

Test for NULL chip_data pointer before attempting to complete an irq move.

Signed-off-by: Prarit Bhargava <prarit@redhat.com>
LKML-Reference: <20100427152434.16193.49104.sendpatchset@prarit.bos.redhat.com>
Acked-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c
index be370593aee8d33a4bdb1966c45bbe0b651904dd..b35c160a4c3b627b5c33e5e0cfd26779eb6f7750 100644 (file)
--- a/arch/x86/kernel/apic/io_apic.c
+++ b/arch/x86/kernel/apic/io_apic.c
@@ -2539,6 +2539,9 @@ void irq_force_complete_move(int irq)
        struct irq_desc *desc = irq_to_desc(irq);
        struct irq_cfg *cfg = desc->chip_data;
 
+       if (!cfg)
+               return;
+
        __irq_complete_move(&desc, cfg->vector);
 }
 #else