You can not select more than 25 topics Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.

Tom Lane 25b692568f Prevent dangling-pointer access when update trigger returns old tuple. ... A before-update row trigger may choose to return the "new" or "old" tuple unmodified. ExecBRUpdateTriggers failed to consider the second possibility, and would proceed to free the "old" tuple even if it was the one returned, leading to subsequent access to already-deallocated memory. In debug builds this reliably leads to an "invalid memory alloc request size" failure; in production builds it might accidentally work, but data corruption is also possible. This is a very old bug. There are probably a couple of reasons it hasn't been noticed up to now. It would be more usual to return NULL if one wanted to suppress the update action; returning "old" is significantly less efficient since the update will occur anyway. Also, none of the standard PLs would ever cause this because they all returned freshly-manufactured tuples even if they were just copying "old". But commit 4b93f5799 changed that for plpgsql, making it possible to see the bug with a plpgsql trigger. Still, this is certainly legal behavior for a trigger function, so it's ExecBRUpdateTriggers's fault not plpgsql's. It seems worth creating a test case that exercises returning "old" directly with a C-language trigger; testing this through plpgsql seems unreliable because its behavior might change again. Report and fix by Rushabh Lathia; regression test case by me. Back-patch to all supported branches. Discussion: https://postgr.es/m/CAGPqQf1P4pjiNPrMof=P_16E-DFjt457j+nH2ex3=nBTew7tXw@mail.gmail.com		8 years ago
..
Makefile	Implement multivariate n-distinct coefficients	9 years ago
aggregatecmds.c	Avoid unnecessary use of pg_strcasecmp for already-downcased identifiers.	8 years ago
alter.c	Replace AclObjectKind with ObjectType	8 years ago
amcmds.c	Update copyright for 2018	8 years ago
analyze.c	Update copyright for 2018	8 years ago
async.c	Update copyright for 2018	8 years ago
cluster.c	Support parallel btree index builds.	8 years ago
collationcmds.c	Avoid unnecessary use of pg_strcasecmp for already-downcased identifiers.	8 years ago
comment.c	Update copyright for 2018	8 years ago
constraint.c	Update copyright for 2018	8 years ago
conversioncmds.c	Replace AclObjectKind with ObjectType	8 years ago
copy.c	Be lazier about partition tuple routing.	8 years ago
createas.c	Update copyright for 2018	8 years ago
dbcommands.c	Message style fix	8 years ago
define.c	Update copyright for 2018	8 years ago
discard.c	Update copyright for 2018	8 years ago
dropcmds.c	Update copyright for 2018	8 years ago
event_trigger.c	Replace AclObjectKind with ObjectType	8 years ago
explain.c	Avoid listing the same ResultRelInfo in more than one EState list.	8 years ago
extension.c	Replace AclObjectKind with ObjectType	8 years ago
foreigncmds.c	Replace AclObjectKind with ObjectType	8 years ago
functioncmds.c	Support parameters in CALL	8 years ago
indexcmds.c	Allow UNIQUE indexes on partitioned tables	8 years ago
lockcmds.c	Replace AclObjectKind with ObjectType	8 years ago
matview.c	Update copyright for 2018	8 years ago
opclasscmds.c	Support all SQL:2011 options for window frame clauses.	8 years ago
operatorcmds.c	Avoid unnecessary use of pg_strcasecmp for already-downcased identifiers.	8 years ago
policy.c	Replace AclObjectKind with ObjectType	8 years ago
portalcmds.c	Remove PortalGetQueryDesc()	8 years ago
prepare.c	Update portal-related memory context names and API	8 years ago
proclang.c	Replace AclObjectKind with ObjectType	8 years ago
publicationcmds.c	Replace AclObjectKind with ObjectType	8 years ago
schemacmds.c	Replace AclObjectKind with ObjectType	8 years ago
seclabel.c	Update copyright for 2018	8 years ago
sequence.c	Update copyright for 2018	8 years ago
statscmds.c	Replace AclObjectKind with ObjectType	8 years ago
subscriptioncmds.c	Replace AclObjectKind with ObjectType	8 years ago
tablecmds.c	Error message improvement	8 years ago
tablespace.c	Replace AclObjectKind with ObjectType	8 years ago
trigger.c	Prevent dangling-pointer access when update trigger returns old tuple.	8 years ago
tsearchcmds.c	Avoid unnecessary use of pg_strcasecmp for already-downcased identifiers.	8 years ago
typecmds.c	Avoid unnecessary use of pg_strcasecmp for already-downcased identifiers.	8 years ago
user.c	Replace AclObjectKind with ObjectType	8 years ago
vacuum.c	Update copyright for 2018	8 years ago
vacuumlazy.c	Update copyright for 2018	8 years ago
variable.c	Update copyright for 2018	8 years ago
view.c	Avoid unnecessary use of pg_strcasecmp for already-downcased identifiers.	8 years ago