2016-09-29 18:00:00 +02:00
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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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pageinspect: Fix handling of page sizes and AM types
This commit fixes a set of issues related to the use of the SQL
functions in this module when the caller is able to pass down raw page
data as input argument:
- The page size check was fuzzy in a couple of places, sometimes
looking after only a sub-range, but what we are looking for is an exact
match on BLCKSZ. After considering a few options here, I have settled
down to do a generalization of get_page_from_raw(). Most of the SQL
functions already used that, and this is not strictly required if not
accessing an 8-byte-wide value from a raw page, but this feels safer in
the long run for alignment-picky environment, particularly if a code
path begins to access such values. This also reduces the number of
strings that need to be translated.
- The BRIN function brin_page_items() uses a Relation but it did not
check the access method of the opened index, potentially leading to
crashes. All the other functions in need of a Relation already did
that.
- Some code paths could fail on elog(), but we should to use ereport()
for failures that can be triggered by the user.
Tests are added to stress all the cases that are fixed as of this
commit, with some junk raw pages (\set VERBOSITY ensures that this works
across all page sizes) and unexpected index types when functions open
relations.
Author: Michael Paquier, Justin Prysby
Discussion: https://postgr.es/m/20220218030020.GA1137@telsasoft.com
Backpatch-through: 10
2022-03-16 03:20:54 +01:00
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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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pageinspect: Add more sanity checks to prevent out-of-bound reads
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
2022-03-27 10:53:59 +02:00
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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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2016-09-29 18:00:00 +02:00
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DROP TABLE test1;
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