11927 Log, or optionally panic, on zero-length kmem allocations
Reviewed by: Dan McDonald <danmcd@joyent.com>
Reviewed by: Jason King <jason.brian.king@gmail.com>

@@ -403,19 +403,22 @@
 sa_add_layout_entry(objset_t *os, sa_attr_type_t *attrs, int attr_count,
     uint64_t lot_num, uint64_t hash, boolean_t zapadd, dmu_tx_t *tx)
 {
         sa_os_t *sa = os->os_sa;
         sa_lot_t *tb, *findtb;
-        int i;
+        int i, size;
         avl_index_t loc;
 
         ASSERT(MUTEX_HELD(&sa->sa_lock));
         tb = kmem_zalloc(sizeof (sa_lot_t), KM_SLEEP);
         tb->lot_attr_count = attr_count;
-        tb->lot_attrs = kmem_alloc(sizeof (sa_attr_type_t) * attr_count,
-            KM_SLEEP);
-        bcopy(attrs, tb->lot_attrs, sizeof (sa_attr_type_t) * attr_count);
+
+        if ((size = sizeof (sa_attr_type_t) * attr_count) != 0) {
+                tb->lot_attrs = kmem_alloc(size, KM_SLEEP);
+                bcopy(attrs, tb->lot_attrs, size);
+        }
+
         tb->lot_num = lot_num;
         tb->lot_hash = hash;
         tb->lot_instance = 0;
 
         if (zapadd) {