Re: BUG #14928: Unchecked SearchSysCacheCopy1() return value

On 2017/11/27 18:13, bianpan2016@163.com wrote:
> The following bug has been logged on the website:
> 
> Bug reference:      14928
> Logged by:          Pan Bian
> Email address:      bianpan2016@163.com
> PostgreSQL version: 10.1
> Operating system:   Linux
> Description:        
> 
> File: postgresql-10.1/src/backend/commands/tablecmds.c
> Function: ATExecDetachPartition
> Line: 13816
> 
> Function SearchSysCacheCopy1() may return a NULL pointer if there is no
> enough memory. But in function ATExecDetachPartition(), its return value is
> not checked, which may result in NULL dereference (see line 13818).
> 
> For your convenience, I copy and paste related codes as follows.
> 
> 13815     classRel = heap_open(RelationRelationId, RowExclusiveLock);
> 13816     tuple = SearchSysCacheCopy1(RELOID,
> 13817                                
> ObjectIdGetDatum(RelationGetRelid(partRel)));
> 13818     Assert(((Form_pg_class) GETSTRUCT(tuple))->relispartition);
> 13819 
> 13820     (void) SysCacheGetAttr(RELOID, tuple,
> Anum_pg_class_relpartbound,
> 13821                            &isnull);
> 13822     Assert(!isnull);

Thanks for the report.  Attached a patch that adds a check that tuple is
valid before trying to dereference it.

Thanks,
Amit