From d9c0c728afe734b7087dbb9a4bc16d5b682d139d Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Fri, 18 Sep 2015 13:55:17 -0400
Subject: [PATCH] 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.
---
src/backend/regex/regcomp.c | 2 +-
src/backend/regex/regexec.c | 6 +++++-
src/include/regex/regguts.h | 2 +-
3 files changed, 7 insertions(+), 3 deletions(-)
diff --git a/src/backend/regex/regcomp.c b/src/backend/regex/regcomp.c
index 6b95975f2be..d137ac0d3d1 100644
--- a/src/backend/regex/regcomp.c
+++ b/src/backend/regex/regcomp.c
@@ -228,7 +228,7 @@ struct vars
struct subre *tree; /* subexpression tree */
struct subre *treechain; /* all tree nodes allocated */
struct subre *treefree; /* any free tree nodes */
- int ntree; /* number of tree nodes */
+ int ntree; /* number of tree nodes, plus one */
struct cvec *cv; /* interface cvec */
struct cvec *cv2; /* utility cvec */
struct subre *lacons; /* lookahead-constraint vector */
diff --git a/src/backend/regex/regexec.c b/src/backend/regex/regexec.c
index efd1e9ba022..8505994747f 100644
--- a/src/backend/regex/regexec.c
+++ b/src/backend/regex/regexec.c
@@ -348,7 +348,11 @@ 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)
diff --git a/src/include/regex/regguts.h b/src/include/regex/regguts.h
index 94e06f041b7..fccaf298bf1 100644
--- a/src/include/regex/regguts.h
+++ b/src/include/regex/regguts.h
@@ -467,7 +467,7 @@ struct guts
size_t nsub; /* copy of re_nsub */
struct subre *tree;
struct cnfa search; /* for fast preliminary search */
- int ntree; /* number of subre's, less one */
+ int ntree; /* number of subre's, plus one */
struct colormap cmap;
int FUNCPTR(compare, (const chr *, const chr *, size_t));
struct subre *lacons; /* lookahead-constraint vector */
--
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