Re: BUG #14927: Unchecked SearchSysCache1() return value

On 2017/11/27 18:01, bianpan2016(at)163(dot)com wrote:
> The following bug has been logged on the website:
>
> Bug reference: 14927
> Logged by: Pan Bian
> Email address: bianpan2016(at)163(dot)com
> PostgreSQL version: 10.1
> Operating system: Linux
> Description:
>
> File: postgresql-10.1/src/backend/catalog/heap.c
> Function: heap_drop_with_catalog
> Line: 1771
>
> Function SearchSysCache1() may return a NULL pointer, but in
> heap_drop_with_catalog(), its return value is not validated before it is
> dereferenced. To avoid NULL dereference, it is better to check the return
> value of SearchSysCache1() against NULL.
>
> For your convenience, I paste related codes as follows:
>
> 1771 tuple = SearchSysCache1(RELOID, ObjectIdGetDatum(relid));
> 1772 if (((Form_pg_class) GETSTRUCT(tuple))->relispartition)
> 1773 {
> 1774 parentOid = get_partition_parent(relid);
> 1775 LockRelationOid(parentOid, AccessExclusiveLock);
> 1776 }
> 1777
> 1778 ReleaseSysCache(tuple);

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

Thanks,
Amit