Re: [PATCH] avoid buffer underflow in errfinish()

On Sat, Mar 23, 2013 at 6:45 PM, Xi Wang <xi(dot)wang(at)gmail(dot)com> wrote:
> A side question: at src/backend/storage/lmgr/proc.c:1150, is there a
> null pointer deference for `autovac'?

Not really. If the deadlock_state is DS_BLOCKED_BY_AUTOVACUUM, there
has to be a blocking autovacuum proc. As in the other case that you
found, though, some code rearrangement would likely make the intent of
the code more clear and avoid future mistakes.

Perhaps something like:

if (deadlock_state == DS_BLOCKED_BY_AUTOVACUUM &&
allow_autovacuum_cancel
&& (autovac = GetBlockingAutoVacuumPgproc()) != NULL)
{
PGXACT *autovac_pgxact =
&ProcGlobal->allPgXact[autovac->pgprocno];
...

--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company