Free SQLSTATE and SQLERRM no earlier than other PL/pgSQL variables.

"RETURN SQLERRM" prompted plpgsql_exec_function() to read from freed
memory.  Back-patch to 9.0 (all supported versions).  Little code ran
between the premature free and the read, so non-assert builds are
unlikely to witness user-visible consequences.

diff --git a/src/pl/plpgsql/src/pl_exec.c b/src/pl/plpgsql/src/pl_exec.c
index dc3bcfe37a9625d0244d86e5729b20d9b36c35d0..6f4fe9185960963c6bd63f472f6baf0488f7a705 100644 (file)
--- a/src/pl/plpgsql/src/pl_exec.c
+++ b/src/pl/plpgsql/src/pl_exec.c
@@ -1129,8 +1129,9 @@ exec_stmt_block(PLpgSQL_execstate *estate, PLpgSQL_stmt_block *block)
                                {
                                        /*
                                         * Initialize the magic SQLSTATE and SQLERRM variables for
-                                        * the exception block. We needn't do this until we have
-                                        * found a matching exception.
+                                        * the exception block; this also frees values from any
+                                        * prior use of the same exception. We needn't do this
+                                        * until we have found a matching exception.
                                         */
                                        PLpgSQL_var *state_var;
                                        PLpgSQL_var *errm_var;
@@ -1154,13 +1155,6 @@ exec_stmt_block(PLpgSQL_execstate *estate, PLpgSQL_stmt_block *block)
 
                                        rc = exec_stmts(estate, exception->action);
 
-                                       free_var(state_var);
-                                       state_var->value = (Datum) 0;
-                                       state_var->isnull = true;
-                                       free_var(errm_var);
-                                       errm_var->value = (Datum) 0;
-                                       errm_var->isnull = true;
-
                                        break;
                                }
                        }

diff --git a/src/test/regress/expected/plpgsql.out b/src/test/regress/expected/plpgsql.out
index 0582e6275ed7cc0aeb28bf7e75e7b8fe3028375a..268626ea0eba25b3757ff25c6b9469d39513cf23 100644 (file)
--- a/src/test/regress/expected/plpgsql.out
+++ b/src/test/regress/expected/plpgsql.out
@@ -2646,9 +2646,21 @@ NOTICE:  P0001 user exception
  
 (1 row)
 
+create function excpt_test4() returns text as $$
+begin
+       begin perform 1/0;
+       exception when others then return sqlerrm; end;
+end; $$ language plpgsql;
+select excpt_test4();
+   excpt_test4    
+------------------
+ division by zero
+(1 row)
+
 drop function excpt_test1();
 drop function excpt_test2();
 drop function excpt_test3();
+drop function excpt_test4();
 -- parameters of raise stmt can be expressions
 create function raise_exprs() returns void as $$
 declare

diff --git a/src/test/regress/sql/plpgsql.sql b/src/test/regress/sql/plpgsql.sql
index 83385090f444f50be8067dd8f2128e191990b124..d76004424e570a4672d935397387afd5fc7d93c7 100644 (file)
--- a/src/test/regress/sql/plpgsql.sql
+++ b/src/test/regress/sql/plpgsql.sql
@@ -2241,11 +2241,19 @@ begin
            raise notice '% %', sqlstate, sqlerrm;
     end;
 end; $$ language plpgsql;
-
 select excpt_test3();
+
+create function excpt_test4() returns text as $$
+begin
+       begin perform 1/0;
+       exception when others then return sqlerrm; end;
+end; $$ language plpgsql;
+select excpt_test4();
+
 drop function excpt_test1();
 drop function excpt_test2();
 drop function excpt_test3();
+drop function excpt_test4();
 
 -- parameters of raise stmt can be expressions
 create function raise_exprs() returns void as $$