Bug#33618 (Crash in sp_rcontext)

Bug 33983 (Stored Procedures: wrong end <label> syntax is accepted)

The server used to crash when REPEAT or another control instruction
was used in conjunction with labels and a LEAVE instruction.

The crash was caused by a missing "pop" of handlers or cursors in the
code representing the stored program. When executing the code in a loop,
this missing "pop" would result in a stack overflow, corrupting memory.

Code generation has been fixed to produce the missing h_pop/c_pop
instructions.

Also, the logic checking that labels at the beginning and the end of a
statement are matched was incorrect, causing Bug 33983.
End labels, when used, must match the label used at the beginning of a block.

mysql-test/t/sp-error.test

@@ -2112,6 +2112,69 @@ SELECT .inexistent();
 SELECT ..inexistent();
 USE test;
 
+#
+# Bug#33983 (Stored Procedures: wrong end <label> syntax is accepted)
+#
+
+--disable_warnings
+drop procedure if exists proc_33983_a;
+drop procedure if exists proc_33983_b;
+drop procedure if exists proc_33983_c;
+drop procedure if exists proc_33983_d;
+--enable_warnings
+
+delimiter |;
+
+--error ER_SP_LABEL_MISMATCH
+create procedure proc_33983_a()
+begin
+  label1:
+    begin
+      label2:
+      begin
+        select 1;
+      end label1;
+    end;
+end|
+
+--error ER_SP_LABEL_MISMATCH
+create procedure proc_33983_b()
+begin
+  label1:
+    repeat
+      label2:
+      repeat
+        select 1;
+      until FALSE end repeat label1;
+    until FALSE end repeat;
+end|
+
+--error ER_SP_LABEL_MISMATCH
+create procedure proc_33983_c()
+begin
+  label1:
+    while TRUE do
+      label2:
+      while TRUE do
+        select 1;
+      end while label1;
+    end while;
+end|
+
+--error ER_SP_LABEL_MISMATCH
+create procedure proc_33983_d()
+begin
+  label1:
+    loop
+      label2:
+      loop
+        select 1;
+      end loop label1;
+    end loop;
+end|
+
+delimiter ;|
+
 #
 # BUG#NNNN: New bug synopsis
 #