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MDEV-22022 Various mangled SQL statements will crash 10.3 to 10.5 debug builds

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Lex_input_stream::scan_ident_delimited() could go beyond the end
of the input when a starting backtick (`) delimiter did not have a
corresponding ending backtick.

Fix: catch the case when yyGet() returns 0, which means
either eof-of-query or straight 0x00 byte inside backticks,
and make the parser fail on syntax error, displaying the left
backtick as the syntax error place.

In case of filename in a script like this:

SET CHARACTER_SET_CLIENT=17; -- 17 is 'filename'
SELECT doc.`Children`.0 FROM t1;

the ending backtick was not recognized as such because my_charlen() returns 0 for
a straight backtick (backticks must normally be encoded as @0060 in filename).

The same fix works for 'filename': the execution skips the backtick
and reaches the end of the query, then yyGet() returns 0.
This fix is OK for now. But eventually 'filename' should either be disallowed
as a parser character set, or fixed to handle encoded punctuation properly.
This commit is contained in:
Alexander Barkov
2020-08-04 09:49:44 +04:00
parent b3e9798ff3
commit d496765903
5 changed files with 43 additions and 1 deletions
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9
mysql-test/main/parser.test
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@ -1538,4 +1538,13 @@ SELECT @@GLOBAL.password;
--error ER_UNKNOWN_SYSTEM_VARIABLE
SELECT @@GLOBAL.role;
--echo #
--echo # MDEV-22022 Various mangled SQL statements will crash 10.3 to 10.5 debug builds
--echo #
--error ER_PARSE_ERROR
EXECUTE IMMEDIATE 'if(`systeminfo /FO LIST';
--error ER_PARSE_ERROR
EXECUTE IMMEDIATE 'if(`systeminfo';
--echo End of 10.3 tests