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Fix low-probability memory leak in regex execution.

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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.
This commit is contained in:
Tom Lane 2015-09-18 13:55:17 -04:00
parent e8e2999470
commit a39331fa57
3 changed files with 7 additions and 3 deletions
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2
src/backend/regex/regcomp.c
View File

@ -228,7 +228,7 @@ struct vars
struct subre *tree; /* subexpression tree */ struct subre *tree; /* subexpression tree */
struct subre *treechain; /* all tree nodes allocated */ struct subre *treechain; /* all tree nodes allocated */
struct subre *treefree; /* any free tree nodes */ 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 *cv; /* interface cvec */
struct cvec *cv2; /* utility cvec */ struct cvec *cv2; /* utility cvec */
struct subre *lacons; /* lookahead-constraint vector */ struct subre *lacons; /* lookahead-constraint vector */

6
src/backend/regex/regexec.c
View File

@ -348,7 +348,11 @@ find(struct vars * v,
(chr **) NULL, &hitend); (chr **) NULL, &hitend);
else else
end = longest(v, d, begin, v->stop, &hitend); end = longest(v, d, begin, v->stop, &hitend);
NOERR(); if (ISERR())
{
freedfa(d);
return v->err;
}
if (hitend && cold == NULL) if (hitend && cold == NULL)
cold = begin; cold = begin;
if (end != NULL) if (end != NULL)

2
src/include/regex/regguts.h
View File

@ -470,7 +470,7 @@ struct guts
size_t nsub; /* copy of re_nsub */ size_t nsub; /* copy of re_nsub */
struct subre *tree; struct subre *tree;
struct cnfa search; /* for fast preliminary search */ 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; struct colormap cmap;
int FUNCPTR(compare, (const chr *, const chr *, size_t)); int FUNCPTR(compare, (const chr *, const chr *, size_t));
struct subre *lacons; /* lookahead-constraint vector */ struct subre *lacons; /* lookahead-constraint vector */