Don't crash in radix_range::replace if val is NULL

Fixes crash when running mapbench.

Don't crash in radix_range::replace if val is NULL
30c6a3bd · David Benjamin · 2ca11e63 · 30c6a3bd
--- a/kernel/radix.cc
+++ b/kernel/radix.cc
@@ -97,7 +97,8 @@ radix_range::replace(u64 start, u64 size, radix_elem *val)
          void* cur = v->ptr().load();
          while (!v->ptr().cmpxch_update(&cur, val))
            ; // spin
-          val->incref();
+          if (val)
+            val->incref();
          if (cur)
            ((radix_elem*) cur)->decref();
        }, true)) {