memory: don't try to adjust endianness for zero length eventfd

There's no need to adjust endianness for zero length eventfd since the data wrote was actually ignored by kernel. So skip the adjust in this case to fix a possible crash when trying to use wildcard mmio eventfd in ppc. Cc: Greg Kurz <[email protected]> Cc: Peter Maydell <[email protected]> Cc: Paolo Bonzini <[email protected]> Acked-by: Greg Kurz <[email protected]> Signed-off-by: Jason Wang <[email protected]> Reviewed-by: Michael S. Tsirkin <[email protected]> Signed-off-by: Michael S. Tsirkin <[email protected]>
cjellick · Nov 12, 2015 · b8aecea · b8aecea
1 parent a6df8ad
commit b8aecea
Showing 1 changed file with 6 additions and 2 deletions.
diff --git a/memory.c b/memory.c
@@ -1688,7 +1688,9 @@ void memory_region_add_eventfd(MemoryRegion *mr,
     };
     unsigned i;
 
-    adjust_endianness(mr, &mrfd.data, size);
+    if (size) {
+        adjust_endianness(mr, &mrfd.data, size);
+    }
     memory_region_transaction_begin();
     for (i = 0; i < mr->ioeventfd_nb; ++i) {
         if (memory_region_ioeventfd_before(mrfd, mr->ioeventfds[i])) {
@@ -1721,7 +1723,9 @@ void memory_region_del_eventfd(MemoryRegion *mr,
     };
     unsigned i;
 
-    adjust_endianness(mr, &mrfd.data, size);
+    if (size) {
+        adjust_endianness(mr, &mrfd.data, size);
+    }
     memory_region_transaction_begin();
     for (i = 0; i < mr->ioeventfd_nb; ++i) {
         if (memory_region_ioeventfd_equal(mrfd, mr->ioeventfds[i])) {