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291e517a4d
A couple of code paths use the special area on the page passed by the function caller, expecting to find some data in it. However, feeding an incorrect page can lead to out-of-bound reads when trying to access the page special area (like a heap page that has no special area, leading PageGetSpecialPointer() to grab a pointer outside the allocated page). The functions used for hash and btree indexes have some protection already against that, while some other functions using a relation OID as argument would make sure that the access method involved is correct, but functions taking in input a raw page without knowing the relation the page is attached to would run into problems. This commit improves the set of checks used in the code paths of BRIN, btree (including one check if a leaf page is found with a non-zero level), GIN and GiST to verify that the page given in input has a special area size that fits with each access method, which is done though PageGetSpecialSize(), becore calling PageGetSpecialPointer(). The scope of the checks done is limited to work with pages that one would pass after getting a block with get_raw_page(), as it is possible to craft byteas that could bypass existing code paths. Having too many checks would also impact the usability of pageinspect, as the existing code is very useful to look at the content details in a corrupted page, so the focus is really to avoid out-of-bound reads as this is never a good thing even with functions whose execution is limited to superusers. The safest approach could be to rework the functions so as these fetch a block using a relation OID and a block number, but there are also cases where using a raw page is useful. Tests are added to cover all the code paths that needed such checks, and an error message for hash indexes is reworded to fit better with what this commit adds. Reported-By: Alexander Lakhin Author: Julien Rouhaud, Michael Paquier Discussion: https://postgr.es/m/16527-ef7606186f0610a1@postgresql.org Discussion: https://postgr.es/m/561e187b-3549-c8d5-03f5-525c14e65bd0@postgrespro.ru Backpatch-through: 10
48 lines
2.1 KiB
PL/PgSQL
48 lines
2.1 KiB
PL/PgSQL
-- The gist_page_opaque_info() function prints the page's LSN. Normally,
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-- that's constant 1 (GistBuildLSN) on every page of a freshly built GiST
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-- index. But with wal_level=minimal, the whole relation is dumped to WAL at
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-- the end of the transaction if it's smaller than wal_skip_threshold, which
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-- updates the LSNs. Wrap the tests on gist_page_opaque_info() in the
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-- same transaction with the CREATE INDEX so that we see the LSNs before
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-- they are possibly overwritten at end of transaction.
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BEGIN;
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-- Create a test table and GiST index.
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CREATE TABLE test_gist AS SELECT point(i,i) p, i::text t FROM
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generate_series(1,1000) i;
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CREATE INDEX test_gist_idx ON test_gist USING gist (p);
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-- Page 0 is the root, the rest are leaf pages
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SELECT * FROM gist_page_opaque_info(get_raw_page('test_gist_idx', 0));
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SELECT * FROM gist_page_opaque_info(get_raw_page('test_gist_idx', 1));
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SELECT * FROM gist_page_opaque_info(get_raw_page('test_gist_idx', 2));
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COMMIT;
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SELECT * FROM gist_page_items(get_raw_page('test_gist_idx', 0), 'test_gist_idx');
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SELECT * FROM gist_page_items(get_raw_page('test_gist_idx', 1), 'test_gist_idx') LIMIT 5;
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-- gist_page_items_bytea prints the raw key data as a bytea. The output of that is
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-- platform-dependent (endianness), so omit the actual key data from the output.
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SELECT itemoffset, ctid, itemlen FROM gist_page_items_bytea(get_raw_page('test_gist_idx', 0));
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-- Failure with non-GiST index.
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CREATE INDEX test_gist_btree on test_gist(t);
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SELECT gist_page_items(get_raw_page('test_gist_btree', 0), 'test_gist_btree');
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-- Failure with various modes.
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-- Suppress the DETAIL message, to allow the tests to work across various
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-- page sizes and architectures.
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\set VERBOSITY terse
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-- invalid page size
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SELECT gist_page_items_bytea('aaa'::bytea);
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SELECT gist_page_items('aaa'::bytea, 'test_gist_idx'::regclass);
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SELECT gist_page_opaque_info('aaa'::bytea);
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-- invalid special area size
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SELECT * FROM gist_page_opaque_info(get_raw_page('test_gist', 0));
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SELECT gist_page_items_bytea(get_raw_page('test_gist', 0));
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SELECT gist_page_items_bytea(get_raw_page('test_gist_btree', 0));
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\set VERBOSITY default
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DROP TABLE test_gist;
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