MDEV-17643 Assertion `nr >= 0.0' failed in Item_sum_std::val_real()

1 files changed, 12 insertions, 0 deletions

diff --git a/sql/item_sum.cc b/sql/item_sum.cc
index b4e31ba012f..5e7ce270dc3 100644
--- a/sql/item_sum.cc
+++ b/sql/item_sum.cc
@@ -1765,6 +1765,18 @@ double Item_sum_std::val_real()
 {
   DBUG_ASSERT(fixed == 1);
   double nr= Item_sum_variance::val_real();
+  if (isnan(nr))
+  {
+    /*
+      variance_fp_recurrence_next() can overflow in some cases and return "nan":
+
+      CREATE OR REPLACE TABLE t1 (a DOUBLE);
+      INSERT INTO t1 VALUES (1.7e+308), (-1.7e+308), (0);
+      SELECT STDDEV_SAMP(a) FROM t1;
+    */
+    null_value= true; // Convert "nan" to NULL
+    return 0;
+  }
   if (my_isinf(nr))
     return DBL_MAX;
   DBUG_ASSERT(nr >= 0.0);