From a375f11c44cf245363f356508f7d5126bdaa18ae Mon Sep 17 00:00:00 2001 From: David Rowley Date: Sat, 18 Apr 2020 14:11:21 +1200 Subject: [PATCH] Fix possible crash with GENERATED ALWAYS columns In some corner cases, this could also lead to corrupted values being included in the tuple. Users who are concerned that they are affected by this should first upgrade and then perform a base backup of their database and restore onto an off-line server. They should then query each table with generated columns to ensure there are no rows where the generated expression does not match a newly calculated version of the GENERATED ALWAYS expression. If no crashes occur and no rows are returned then you're not affected. Fixes bug #16369. Reported-by: Cameron Ezell Discussion: https://postgr.es/m/16369-5845a6f1bef59884@postgresql.org Backpatch-through: 12 (where GENERATED ALWAYS columns were added.) --- src/backend/executor/nodeModifyTable.c | 7 +++++++ src/test/regress/expected/generated.out | 12 ++++++++++++ src/test/regress/sql/generated.sql | 7 +++++++ 3 files changed, 26 insertions(+) diff --git a/src/backend/executor/nodeModifyTable.c b/src/backend/executor/nodeModifyTable.c index 212b12ab51..08609f23dd 100644 --- a/src/backend/executor/nodeModifyTable.c +++ b/src/backend/executor/nodeModifyTable.c @@ -311,6 +311,13 @@ ExecComputeStoredGenerated(EState *estate, TupleTableSlot *slot) val = ExecEvalExpr(resultRelInfo->ri_GeneratedExprs[i], econtext, &isnull); + /* + * We must make a copy of val as we have no guarantees about where + * memory for a pass-by-reference Datum is located. + */ + if (!isnull) + val = datumCopy(val, attr->attbyval, attr->attlen); + values[i] = val; nulls[i] = isnull; } diff --git a/src/test/regress/expected/generated.out b/src/test/regress/expected/generated.out index 8cffef0477..f87c86a8ce 100644 --- a/src/test/regress/expected/generated.out +++ b/src/test/regress/expected/generated.out @@ -320,6 +320,18 @@ SELECT * FROM gtest2; 1 | (1 row) +-- simple column reference for varlena types +CREATE TABLE gtest_varlena (a varchar, b varchar GENERATED ALWAYS AS (a) STORED); +INSERT INTO gtest_varlena (a) VALUES('01234567890123456789'); +INSERT INTO gtest_varlena (a) VALUES(NULL); +SELECT * FROM gtest_varlena ORDER BY a; + a | b +----------------------+---------------------- + 01234567890123456789 | 01234567890123456789 + | +(2 rows) + +DROP TABLE gtest_varlena; -- composite types CREATE TYPE double_int as (a int, b int); CREATE TABLE gtest4 ( diff --git a/src/test/regress/sql/generated.sql b/src/test/regress/sql/generated.sql index ff5c8607de..bdcedbb991 100644 --- a/src/test/regress/sql/generated.sql +++ b/src/test/regress/sql/generated.sql @@ -145,6 +145,13 @@ CREATE TABLE gtest2 (a int PRIMARY KEY, b int GENERATED ALWAYS AS (NULL) STORED) INSERT INTO gtest2 VALUES (1); SELECT * FROM gtest2; +-- simple column reference for varlena types +CREATE TABLE gtest_varlena (a varchar, b varchar GENERATED ALWAYS AS (a) STORED); +INSERT INTO gtest_varlena (a) VALUES('01234567890123456789'); +INSERT INTO gtest_varlena (a) VALUES(NULL); +SELECT * FROM gtest_varlena ORDER BY a; +DROP TABLE gtest_varlena; + -- composite types CREATE TYPE double_int as (a int, b int); CREATE TABLE gtest4 (