From d35631e37cab25e57f9402fdf208176a1951c87f Mon Sep 17 00:00:00 2001 From: Andres Freund Date: Mon, 23 Mar 2020 13:57:43 -0700 Subject: [PATCH] Fix potential crash after constraint violation errors in partitioned tables. During the reporting of constraint violations for partitioned tables, ExecPartitionCheckEmitError(), ExecConstraints(), ExecWithCheckOptions() set the slot descriptor of the input slot to the root partition's tuple desc. That's generally problematic when the slot could be used by other routines, but can cause crashes after the introduction of slots with "fixed" tuple descriptors in ad7dbee368a. The problem likely escaped detection so far for two reasons: First, currently the only known way that these routines are used with a partitioned table that is not "owned" by partitioning code is when "fast defaults" are used for the child partition. Second, as an error is raised afterwards, an "external" slot that had its descriptor changed, is very unlikely to continue being used. Even though the issue currently is only known to cause a crash for 11 (as that has both fast defaults and "fixed" slot descriptors), it seems worth applying the fix to 10 too. Potentially changing random slots is hazardous. Regression tests will be added in a separate commit, as it seems best to add them for master and 12 too. Reported-By: Daniel WM Author: Andres Freund Bug: #16293 Discussion: https://postgr.es/m/16293-26f5777d10143a66@postgresql.org Backpatch: 11, 10 only --- src/backend/executor/execMain.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) diff --git a/src/backend/executor/execMain.c b/src/backend/executor/execMain.c index 66cac46acf..8daf0fe933 100644 --- a/src/backend/executor/execMain.c +++ b/src/backend/executor/execMain.c @@ -1932,7 +1932,8 @@ ExecPartitionCheckEmitError(ResultRelInfo *resultRelInfo, if (map != NULL) { tuple = do_convert_tuple(tuple, map); - ExecSetSlotDescriptor(slot, tupdesc); + /* one off slot for building error message */ + slot = MakeTupleTableSlot(tupdesc); ExecStoreTuple(tuple, slot, InvalidBuffer, false); } } @@ -2011,7 +2012,8 @@ ExecConstraints(ResultRelInfo *resultRelInfo, if (map != NULL) { tuple = do_convert_tuple(tuple, map); - ExecSetSlotDescriptor(slot, tupdesc); + /* one off slot for building error message */ + slot = MakeTupleTableSlot(tupdesc); ExecStoreTuple(tuple, slot, InvalidBuffer, false); } } @@ -2059,7 +2061,8 @@ ExecConstraints(ResultRelInfo *resultRelInfo, if (map != NULL) { tuple = do_convert_tuple(tuple, map); - ExecSetSlotDescriptor(slot, tupdesc); + /* one off slot for building error message */ + slot = MakeTupleTableSlot(tupdesc); ExecStoreTuple(tuple, slot, InvalidBuffer, false); } } @@ -2165,7 +2168,8 @@ ExecWithCheckOptions(WCOKind kind, ResultRelInfo *resultRelInfo, if (map != NULL) { tuple = do_convert_tuple(tuple, map); - ExecSetSlotDescriptor(slot, tupdesc); + /* one off slot for building error message */ + slot = MakeTupleTableSlot(tupdesc); ExecStoreTuple(tuple, slot, InvalidBuffer, false); } }