Merge 11.4 into 11.8 (Q2 2026 release)

Null-merge MDEV-39240 (as if removed by MDEV-32188).

MDEV-39240 fixed a replication compatibility issue with 32-bit
unsigned timestamps that only existed because MDEV-32188 was a
preview feature in 11.4. In 11.8, MDEV-32188 is fully released
and stable, so MDEV-39240 is inapplicable and excluded.

Author: itzanway

libmariadb

@@ -534,7 +534,19 @@ int sp_lex_keeper::validate_lex_and_exec_core(THD *thd, uint *nextp,
     m_first_execution= false;
 
     if (!rc)
+    {
+      /*
+       sp_lex_instr is re-parsed after the metadata change, which sets up a new
+       mem_root for reparsing. Once the sp_lex_instr is reparsed and re-executed
+       (via reset_lex_and_exec_core) it should be marked as read-only to enforce
+       sp memory root protection.
+       */
+#ifdef PROTECT_STATEMENT_MEMROOT
+      if (rerun_the_same_instr && instr->mem_root)
+        instr->mem_root->flags |= ROOT_FLAG_READ_ONLY;
+#endif
       break;
+    }
 
     /*
       Raise the error upper level in case: