From 7e0b9ed6c52bc19221c401859a2cfc3c8b07b43f Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Thu, 13 Jun 2013 13:11:35 -0400 Subject: [PATCH] Only install a portal's ResourceOwner if it actually has one. In most scenarios a portal without a ResourceOwner is dead and not subject to any further execution, but a portal for a cursor WITH HOLD remains in existence with no ResourceOwner after the creating transaction is over. In this situation, if we attempt to "execute" the portal directly to fetch data from it, we were setting CurrentResourceOwner to NULL, leading to a segfault if the datatype output code did anything that required a resource owner (such as trying to fetch system catalog entries that weren't already cached). The case appears to be impossible to provoke with stock libpq, but psqlODBC at least is able to cause it when working with held cursors. Simplest fix is to just skip the assignment to CurrentResourceOwner, so that any resources used by the data output operations will be managed by the transaction-level resource owner instead. For consistency I changed all the places that install a portal's resowner as current, even though some of them are probably not reachable with a held cursor's portal. Per report from Joshua Berry (with thanks to Hiroshi Inoue for developing a self-contained test case). Back-patch to all supported versions. --- src/backend/commands/portalcmds.c | 6 ++++-- src/backend/tcop/pquery.c | 9 ++++++--- 2 files changed, 10 insertions(+), 5 deletions(-) diff --git a/src/backend/commands/portalcmds.c b/src/backend/commands/portalcmds.c index b5ce87a29d..03c7f0722c 100644 --- a/src/backend/commands/portalcmds.c +++ b/src/backend/commands/portalcmds.c @@ -274,7 +274,8 @@ PortalCleanup(Portal portal) saveResourceOwner = CurrentResourceOwner; PG_TRY(); { - CurrentResourceOwner = portal->resowner; + if (portal->resowner) + CurrentResourceOwner = portal->resowner; ExecutorFinish(queryDesc); ExecutorEnd(queryDesc); FreeQueryDesc(queryDesc); @@ -349,7 +350,8 @@ PersistHoldablePortal(Portal portal) PG_TRY(); { ActivePortal = portal; - CurrentResourceOwner = portal->resowner; + if (portal->resowner) + CurrentResourceOwner = portal->resowner; PortalContext = PortalGetHeapMemory(portal); MemoryContextSwitchTo(PortalContext); diff --git a/src/backend/tcop/pquery.c b/src/backend/tcop/pquery.c index ce5e5e29dd..30140b1873 100644 --- a/src/backend/tcop/pquery.c +++ b/src/backend/tcop/pquery.c @@ -478,7 +478,8 @@ PortalStart(Portal portal, ParamListInfo params, PG_TRY(); { ActivePortal = portal; - CurrentResourceOwner = portal->resowner; + if (portal->resowner) + CurrentResourceOwner = portal->resowner; PortalContext = PortalGetHeapMemory(portal); oldContext = MemoryContextSwitchTo(PortalGetHeapMemory(portal)); @@ -762,7 +763,8 @@ PortalRun(Portal portal, long count, bool isTopLevel, PG_TRY(); { ActivePortal = portal; - CurrentResourceOwner = portal->resowner; + if (portal->resowner) + CurrentResourceOwner = portal->resowner; PortalContext = PortalGetHeapMemory(portal); MemoryContextSwitchTo(PortalContext); @@ -1411,7 +1413,8 @@ PortalRunFetch(Portal portal, PG_TRY(); { ActivePortal = portal; - CurrentResourceOwner = portal->resowner; + if (portal->resowner) + CurrentResourceOwner = portal->resowner; PortalContext = PortalGetHeapMemory(portal); oldContext = MemoryContextSwitchTo(PortalContext); -- 2.40.0