From afcc8772edcec687d87b6f762ca6113229af7291 Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Fri, 8 Jan 2021 12:16:00 -0500 Subject: Fix ancient bug in parsing of BRE-mode regular expressions. brenext(), when parsing a '*' quantifier, forgot to return any "value" for the token; per the equivalent case in next(), it should return value 1 to indicate that greedy rather than non-greedy behavior is wanted. The result is that the compiled regexp could behave like 'x*?' rather than the intended 'x*', if we were unlucky enough to have a zero in v->nextvalue at this point. That seems to happen with some reliability if we have '.*' at the beginning of a BRE-mode regexp, although that depends on the initial contents of a stack-allocated struct, so it's not guaranteed to fail. Found by Alexander Lakhin using valgrind testing. This bug seems to be aboriginal in Spencer's code, so back-patch all the way. Discussion: https://postgr.es/m/16814-6c5e3edd2bdf0d50@postgresql.org --- src/test/modules/test_regex/sql/test_regex.sql | 2 ++ 1 file changed, 2 insertions(+) (limited to 'src/test/modules/test_regex/sql') diff --git a/src/test/modules/test_regex/sql/test_regex.sql b/src/test/modules/test_regex/sql/test_regex.sql index 4676cd1a060..1a2bfa62357 100644 --- a/src/test/modules/test_regex/sql/test_regex.sql +++ b/src/test/modules/test_regex/sql/test_regex.sql @@ -214,6 +214,8 @@ select * from test_regex('a?*', '', '-'); select * from test_regex('a+*', '', '-'); -- expectError 7.15 - a*+ BADRPT select * from test_regex('a*+', '', '-'); +-- test for ancient brenext() bug; not currently in Tcl +select * from test_regex('.*b', 'aaabbb', 'b'); -- doing 8 "braces" -- cgit v1.2.3