From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Fri, 18 Sep 2015 17:55:17 +0000 (-0400)
Subject: Fix low-probability memory leak in regex execution.
X-Git-Tag: REL9_1_19~31
X-Git-Url: http://git.postgresql.org/gitweb/?a=commitdiff_plain;h=28c396134e0640e21610a984b89393825753b30d;p=postgresql.git

Fix low-probability memory leak in regex execution.

After an internal failure in shortest() or longest() while pinning down the
exact location of a match, find() forgot to free the DFA structure before
returning.  This is pretty unlikely to occur, since we just successfully
ran the "search" variant of the DFA; but it could happen, and it would
result in a session-lifespan memory leak since this code uses malloc()
directly.  Problem seems to have been aboriginal in Spencer's library,
so back-patch all the way.

In passing, correct a thinko in a comment I added awhile back about the
meaning of the "ntree" field.

I happened across these issues while comparing our code to Tcl's version
of the library.
---

diff --git a/src/backend/regex/regexec.c b/src/backend/regex/regexec.c
index ee9984d6c07..7b98b18da7e 100644
--- a/src/backend/regex/regexec.c
+++ b/src/backend/regex/regexec.c
@@ -326,7 +326,11 @@ find(struct vars * v,
 						   (chr **) NULL, &hitend);
 		else
 			end = longest(v, d, begin, v->stop, &hitend);
-		NOERR();
+		if (ISERR())
+		{
+			freedfa(d);
+			return v->err;
+		}
 		if (hitend && cold == NULL)
 			cold = begin;
 		if (end != NULL)