config: fix some common issues with path() usage

None of the callers check that the allocation in path() failed, so let's
check in path() and abort instead of failing.

Along those lines, none of the callers seem to acknowledge that the
returned string needs to be free()d -- let's do that as well.  There are
a couple not addressed in this commit that will be addressed in a future
commit by pushing the path() call down into moveifchanged() instead and
freeing it properly there.

CID:	1505271, 1505250, 1505279
Reviewed by:	emaste, imp

2 files changed, 11 insertions, 2 deletions

diff --git a/usr.sbin/config/main.cc b/usr.sbin/config/main.cc
index ef24d373c8b0..f155b7c5387a 100644
--- a/usr.sbin/config/main.cc
+++ b/usr.sbin/config/main.cc
@@ -457,6 +457,8 @@ path(const char *file)
 		asprintf(&cp, "%s/%s", destdir, file);
 	else
 		cp = strdup(destdir);
+	if (cp == NULL)
+		err(EXIT_FAILURE, "malloc");
 	return (cp);
 }
 
@@ -553,6 +555,8 @@ configfile(void)
 	fo = fopen(p, "w");
 	if (!fo)
 		err(2, "%s", p);
+	free(p);
+
 	if (filebased) {
 		/* Is needed, can be used for backward compatibility. */
 		configfile_filebased(cfg);
@@ -673,8 +677,10 @@ cleanheaders(char *p)
 		if (hl)
 			continue;
 		printf("Removing stale header: %s\n", dp->d_name);
-		if (unlink(path(dp->d_name)) == -1)
+		p = path(dp->d_name);
+		if (unlink(p) == -1)
 			warn("unlink %s", dp->d_name);
+		free(p);
 	}
 	(void)closedir(dirp);
 }
diff --git a/usr.sbin/config/mkoptions.cc b/usr.sbin/config/mkoptions.cc
index f45c1026417c..134c09c2d074 100644
--- a/usr.sbin/config/mkoptions.cc
+++ b/usr.sbin/config/mkoptions.cc
@@ -294,6 +294,7 @@ tooption(char *name)
 	static char hbuf[MAXPATHLEN];
 	char nbuf[MAXPATHLEN];
 	struct opt_list *po;
+	char *fpath;
 
 	/* "cannot happen"?  the otab list should be complete.. */
 	(void)strlcpy(nbuf, "options.h", sizeof(nbuf));
@@ -305,7 +306,9 @@ tooption(char *name)
 		}
 	}
 
-	(void)strlcpy(hbuf, path(nbuf), sizeof(hbuf));
+	fpath = path(nbuf);
+	(void)strlcpy(hbuf, fpath, sizeof(hbuf));
+	free(fpath);
 	return (hbuf);
 }