[Qemu-devel][PATCH] ppc/spapr_events: fix potential NULL pointer dereference in rtas_event_log_dequeue

[pannengyuan]

From: PanNengyuan <pannengy...@huawei.com>

source is being dereferenced before it is null checked, hence there is a
potential null pointer dereference.

This fixes:
        360
    CID 68911917: (NULL_RETURNS)
        361. dereference: Dereferencing "source", which is known to be
        "NULL".
        361        if (source->mask & event_mask) {
        362            break;
        363        }

Reported-by: Euler Robot <euler.ro...@huawei.com>
Signed-off-by: PanNengyuan <pannengy...@huawei.com>
---
 hw/ppc/spapr_events.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/hw/ppc/spapr_events.c b/hw/ppc/spapr_events.c
index 0e4c195..febd2ef 100644
--- a/hw/ppc/spapr_events.c
+++ b/hw/ppc/spapr_events.c
@@ -358,7 +358,7 @@ static SpaprEventLogEntry 
*rtas_event_log_dequeue(SpaprMachineState *spapr,
             rtas_event_log_to_source(spapr,
                                      spapr_event_log_entry_type(entry));
 
-        if (source->mask & event_mask) {
+        if (source && (source->mask & event_mask)) {
             break;
         }
     }
-- 
2.7.2.windows.1