Prevent corner-case core dump in rfree().

rfree() failed to cope with the case that pg_regcomp() had initialized the
regex_t struct but then failed to allocate any memory for re->re_guts (ie,
the first malloc call in pg_regcomp() failed).  It would try to touch the
guts struct anyway, and thus dump core.  This is a sufficiently narrow
corner case that it's not surprising it's never been seen in the field;
but still a bug is a bug, so patch all active branches.

Noted while investigating whether we need to call pg_regfree after a
failure return from pg_regcomp.  Other than this bug, it turns out we
don't, so adjust comments appropriately.

diff --git a/src/backend/regex/regcomp.c b/src/backend/regex/regcomp.c
index 593184f736f92f16b14d5f56d91ac41d6b94f9c8..715d9fac4de0f6b2acd63bc767a9d534aa572065 100644 (file)
--- a/src/backend/regex/regcomp.c
+++ b/src/backend/regex/regcomp.c
@@ -276,6 +276,9 @@ static struct fns functions = {
 
 /*
  * pg_regcomp - compile regular expression
+ *
+ * Note: on failure, no resources remain allocated, so pg_regfree()
+ * need not be applied to re.
  */
 int
 pg_regcomp(regex_t *re,
@@ -1846,15 +1849,18 @@ rfree(regex_t *re)
        g = (struct guts *) re->re_guts;
        re->re_guts = NULL;
        re->re_fns = NULL;
-       g->magic = 0;
-       freecm(&g->cmap);
-       if (g->tree != NULL)
-               freesubre((struct vars *) NULL, g->tree);
-       if (g->lacons != NULL)
-               freelacons(g->lacons, g->nlacons);
-       if (!NULLCNFA(g->search))
-               freecnfa(&g->search);
-       FREE(g);
+       if (g != NULL)
+       {
+               g->magic = 0;
+               freecm(&g->cmap);
+               if (g->tree != NULL)
+                       freesubre((struct vars *) NULL, g->tree);
+               if (g->lacons != NULL)
+                       freelacons(g->lacons, g->nlacons);
+               if (!NULLCNFA(g->search))
+                       freecnfa(&g->search);
+               FREE(g);
+       }
 }
 
 #ifdef REG_DEBUG

diff --git a/src/backend/utils/adt/regexp.c b/src/backend/utils/adt/regexp.c
index 405ca6c8e634a7e3252520d7867b15280aa9e7fa..84c9d4fee7b332410d039c150ace6eae0a54d214 100644 (file)
--- a/src/backend/utils/adt/regexp.c
+++ b/src/backend/utils/adt/regexp.c
@@ -182,9 +182,8 @@ RE_compile_and_cache(text *text_re, int cflags)
 
        if (regcomp_result != REG_OKAY)
        {
-               /* re didn't compile */
+               /* re didn't compile (no need for pg_regfree, if so) */
                pg_regerror(regcomp_result, &re_temp.cre_re, errMsg, sizeof(errMsg));
-               /* XXX should we pg_regfree here? */
                ereport(ERROR,
                                (errcode(ERRCODE_INVALID_REGULAR_EXPRESSION),
                                 errmsg("invalid regular expression: %s", errMsg)));