postgrespro.git / summary / log / commit / refs

commit    1ced082b95b339e49fc3d9f15474f816e7a9cfb1
Author:   Tom Lane <tgl@sss.pgh.pa.us>
Date:     Fri Aug 16 00:04:19 2019 +0000

    Prevent possible double-free when update trigger returns old tuple.
    
    This is a variant of the problem fixed in commit 25b692568, which
    unfortunately we failed to detect at the time.  If an update trigger
    returns the "old" tuple, as it's entitled to do, then a subsequent
    iteration of the loop in ExecBRUpdateTriggers would have "oldtuple"
    equal to "trigtuple" and would fail to notice that it shouldn't
    free that.
    
    In addition to fixing the code, extend the test case added by
    25b692568 so that it covers multiple-trigger-iterations cases.
    
    This problem does not manifest in v12/HEAD, as a result of the
    relevant code having been largely rewritten for slotification.
    However, include the test case into v12/HEAD anyway, since this
    is clearly an area that someone could break again in future.
    
    Per report from Piotr Gabriel Kosinski.  Back-patch into all
    supported branches, since the bug seems quite old.
    
    Diagnosis and code fix by Thomas Munro, test case by me.
    
    Discussion: https://postgr.es/m/CAFMLSdP0rd7LqC3j-H6Fh51FYSt5A10DDh-3=W4PPc4LLUQ8YQ@mail.gmail.com


 src/test/regress/expected/triggers.out | 70 ++++++++++++++++++++++++++++++++++
 src/test/regress/sql/triggers.sql      | 35 +++++++++++++++++
 2 files changed, 105 insertions(+)

diff --git a/src/test/regress/expected/triggers.out b/src/test/regress/expected/triggers.out
index c64151ba09..1e4053ceed 100644
--- a/src/test/regress/expected/triggers.out
+++ b/src/test/regress/expected/triggers.out
@@ -144,6 +144,76 @@ select * from trigtest;
 ----+----
 (0 rows)
 
+-- Also check what happens when such a trigger runs before or after others
+create function f1_times_10() returns trigger as
+$$ begin new.f1 := new.f1 * 10; return new; end $$ language plpgsql;
+create trigger trigger_alpha
+	before insert or update on trigtest
+	for each row execute procedure f1_times_10();
+insert into trigtest values(1, 'foo');
+select * from trigtest;
+ f1 | f2  
+----+-----
+ 10 | foo
+(1 row)
+
+update trigtest set f2 = f2 || 'bar';
+select * from trigtest;
+ f1 | f2  
+----+-----
+ 10 | foo
+(1 row)
+
+delete from trigtest;
+select * from trigtest;
+ f1 | f2 
+----+----
+(0 rows)
+
+create trigger trigger_zed
+	before insert or update on trigtest
+	for each row execute procedure f1_times_10();
+insert into trigtest values(1, 'foo');
+select * from trigtest;
+ f1  | f2  
+-----+-----
+ 100 | foo
+(1 row)
+
+update trigtest set f2 = f2 || 'bar';
+select * from trigtest;
+  f1  | f2  
+------+-----
+ 1000 | foo
+(1 row)
+
+delete from trigtest;
+select * from trigtest;
+ f1 | f2 
+----+----
+(0 rows)
+
+drop trigger trigger_alpha on trigtest;
+insert into trigtest values(1, 'foo');
+select * from trigtest;
+ f1 | f2  
+----+-----
+ 10 | foo
+(1 row)
+
+update trigtest set f2 = f2 || 'bar';
+select * from trigtest;
+ f1  | f2  
+-----+-----
+ 100 | foo
+(1 row)
+
+delete from trigtest;
+select * from trigtest;
+ f1 | f2 
+----+----
+(0 rows)
+
 drop table trigtest;
 create sequence ttdummy_seq increment 10 start 0 minvalue 0;
 create table tttest (
diff --git a/src/test/regress/sql/triggers.sql b/src/test/regress/sql/triggers.sql
index 4534dc9ebe..c21b6c124e 100644
--- a/src/test/regress/sql/triggers.sql
+++ b/src/test/regress/sql/triggers.sql
@@ -117,6 +117,41 @@ select * from trigtest;
 delete from trigtest;
 select * from trigtest;
 
+-- Also check what happens when such a trigger runs before or after others
+create function f1_times_10() returns trigger as
+$$ begin new.f1 := new.f1 * 10; return new; end $$ language plpgsql;
+
+create trigger trigger_alpha
+	before insert or update on trigtest
+	for each row execute procedure f1_times_10();
+
+insert into trigtest values(1, 'foo');
+select * from trigtest;
+update trigtest set f2 = f2 || 'bar';
+select * from trigtest;
+delete from trigtest;
+select * from trigtest;
+
+create trigger trigger_zed
+	before insert or update on trigtest
+	for each row execute procedure f1_times_10();
+
+insert into trigtest values(1, 'foo');
+select * from trigtest;
+update trigtest set f2 = f2 || 'bar';
+select * from trigtest;
+delete from trigtest;
+select * from trigtest;
+
+drop trigger trigger_alpha on trigtest;
+
+insert into trigtest values(1, 'foo');
+select * from trigtest;
+update trigtest set f2 = f2 || 'bar';
+select * from trigtest;
+delete from trigtest;
+select * from trigtest;
+
 drop table trigtest;
 
 create sequence ttdummy_seq increment 10 start 0 minvalue 0;


[parent: fe9b7b2fe597]