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 39866edca38bca637f9c4131ba21afb7e2c82de7..9601345c84a32915df2179c715ad16c068450506 100644 (file)
--- a/src/pl/plpgsql/src/pl_exec.c
+++ b/src/pl/plpgsql/src/pl_exec.c
@@ -1220,8 +1220,9 @@ 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;
@@ -1245,13 +1246,6 @@ 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 7feea0ac476afc452ee57a9c7446a2873df49187..844f6fc82aaf600d30aca95a559f28d5705fee39 100644 (file)
--- a/src/test/regress/expected/plpgsql.out
+++ b/src/test/regress/expected/plpgsql.out
@@ -2644,9 +2644,21 @@ 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 0f8465faa470d28c1764cd5625f5db814d5c46e6..6b3264b7bc0268afb27f5e3672dda606ea381a7f 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 $$