database/postgres
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2025-06-29 10:41:53 +03:00
Code Activity

Handle unexpected query results, especially NULLs, safely in connectby().

Browse Source 
connectby() didn't adequately check that the constructed SQL query returns
what it's expected to; in fact, since commit 08c33c426b it wasn't
checking that at all.  This could result in a null-pointer-dereference
crash if the constructed query returns only one column instead of the
expected two.  Less excitingly, it could also result in surprising data
conversion failures if the constructed query returned values that were
not I/O-conversion-compatible with the types specified by the query
calling connectby().

In all branches, insist that the query return at least two columns;
this seems like a minimal sanity check that can't break any reasonable
use-cases.

In HEAD, insist that the constructed query return the types specified by
the outer query, including checking for typmod incompatibility, which the
code never did even before it got broken.  This is to hide the fact that
the implementation does a conversion to text and back; someday we might
want to improve that.

In back branches, leave that alone, since adding a type check in a minor
release is more likely to break things than make people happy.  Type
inconsistencies will continue to work so long as the actual type and
declared type are I/O representation compatible, and otherwise will fail
the same way they used to.

Also, in all branches, be on guard for NULL results from the constructed
query, which formerly would cause null-pointer dereference crashes.
We now print the row with the NULL but don't recurse down from it.

In passing, get rid of the rather pointless idea that
build_tuplestore_recursively() should return the same tuplestore that's
passed to it.

Michael Paquier, adjusted somewhat by me
This commit is contained in:
Tom Lane
2015-01-29 20:18:42 -05:00
parent 8251acf23b
commit 66cc746809
3 changed files with 116 additions and 83 deletions
Download Patch File Download Diff File Expand all files Collapse all files

16
contrib/tablefunc/sql/tablefunc.sql
View File

@ -179,6 +179,22 @@ SELECT * FROM connectby('connectby_int', 'keyid', 'parent_keyid', '2', 0, '~') A
-- infinite recursion failure avoided by depth limit
SELECT * FROM connectby('connectby_int', 'keyid', 'parent_keyid', '2', 4, '~') AS t(keyid int, parent_keyid int, level int, branch text);
-- should fail as first two columns must have the same type
SELECT * FROM connectby('connectby_int', 'keyid', 'parent_keyid', '2', 0, '~') AS t(keyid text, parent_keyid int, level int, branch text);
-- should fail as key field datatype should match return datatype
SELECT * FROM connectby('connectby_int', 'keyid', 'parent_keyid', '2', 0, '~') AS t(keyid float8, parent_keyid float8, level int, branch text);
-- tests for values using custom queries
-- query with one column - failed
SELECT * FROM connectby('connectby_int', '1; --', 'parent_keyid', '2', 0) AS t(keyid int, parent_keyid int, level int);
-- query with two columns first value as NULL
SELECT * FROM connectby('connectby_int', 'NULL::int, 1::int; --', 'parent_keyid', '2', 0) AS t(keyid int, parent_keyid int, level int);
-- query with two columns second value as NULL
SELECT * FROM connectby('connectby_int', '1::int, NULL::int; --', 'parent_keyid', '2', 0) AS t(keyid int, parent_keyid int, level int);
-- query with two columns, both values as NULL
SELECT * FROM connectby('connectby_int', 'NULL::int, NULL::int; --', 'parent_keyid', '2', 0) AS t(keyid int, parent_keyid int, level int);
-- test for falsely detected recursion
DROP TABLE connectby_int;
CREATE TABLE connectby_int(keyid int, parent_keyid int);