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3d4d6dee07
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
66 lines
2.1 KiB
Plaintext
66 lines
2.1 KiB
Plaintext
CREATE TABLE test1 (a int, b text);
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INSERT INTO test1 VALUES (1, 'one');
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CREATE INDEX test1_a_idx ON test1 USING brin (a);
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SELECT brin_page_type(get_raw_page('test1_a_idx', 0));
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brin_page_type
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----------------
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meta
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(1 row)
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SELECT brin_page_type(get_raw_page('test1_a_idx', 1));
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brin_page_type
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----------------
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revmap
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(1 row)
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SELECT brin_page_type(get_raw_page('test1_a_idx', 2));
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brin_page_type
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----------------
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regular
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(1 row)
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SELECT * FROM brin_metapage_info(get_raw_page('test1_a_idx', 0));
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magic | version | pagesperrange | lastrevmappage
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------------+---------+---------------+----------------
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0xA8109CFA | 1 | 128 | 1
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(1 row)
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SELECT * FROM brin_metapage_info(get_raw_page('test1_a_idx', 1));
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ERROR: page is not a BRIN page of type "metapage"
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DETAIL: Expected special type 0000f091, got 0000f092.
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SELECT * FROM brin_revmap_data(get_raw_page('test1_a_idx', 0)) LIMIT 5;
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ERROR: page is not a BRIN page of type "revmap"
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DETAIL: Expected special type 0000f092, got 0000f091.
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SELECT * FROM brin_revmap_data(get_raw_page('test1_a_idx', 1)) LIMIT 5;
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pages
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-------
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(2,1)
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(0,0)
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(0,0)
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(0,0)
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(0,0)
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(5 rows)
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SELECT * FROM brin_page_items(get_raw_page('test1_a_idx', 2), 'test1_a_idx')
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ORDER BY blknum, attnum LIMIT 5;
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itemoffset | blknum | attnum | allnulls | hasnulls | placeholder | value
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------------+--------+--------+----------+----------+-------------+----------
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1 | 0 | 1 | f | f | f | {1 .. 1}
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(1 row)
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-- Failure for non-BRIN index.
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CREATE INDEX test1_a_btree ON test1 (a);
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SELECT brin_page_items(get_raw_page('test1_a_btree', 0), 'test1_a_btree');
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ERROR: "test1_a_btree" is not a BRIN index
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-- Mask DETAIL messages as these are not portable across architectures.
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\set VERBOSITY terse
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-- Invalid special area size
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SELECT brin_page_type(get_raw_page('test1', 0));
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ERROR: input page is not a valid BRIN page
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SELECT * FROM brin_metapage_info(get_raw_page('test1', 0));
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ERROR: input page is not a valid BRIN page
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SELECT * FROM brin_revmap_data(get_raw_page('test1', 0));
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ERROR: input page is not a valid BRIN page
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\set VERBOSITY default
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DROP TABLE test1;
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