pw: fix setmode(NULL) crash when homemode is a boolean value

usr.sbin/pw/pw_conf.c

@@ -298,10 +298,16 @@ read_userconfig(char const * file)
 					? "/home" : newstr(q);
 				break;
 			case _UC_HOMEMODE:
-				modeset = setmode(q);
-				config.homemode = (q == NULL || !boolean_val(q, 1))
-					? _DEF_DIRMODE : getmode(modeset, _DEF_DIRMODE);
-				free(modeset);
+				if (q == NULL || !boolean_val(q, 1)) {
+					config.homemode = _DEF_DIRMODE;
+				} else {
+					modeset = setmode(q);
+					if (modeset == NULL)
+						errx(1, "Invalid mode: '%s'", q);
+					config.homemode = getmode(modeset,
+					    _DEF_DIRMODE);
+					free(modeset);
+				}
 				break;
 			case _UC_SHELLPATH:
 				config.shelldir = (q == NULL || !boolean_val(q, 1))

usr.sbin/pw/tests/pw_config_test.sh

@@ -19,7 +19,19 @@ modify_config_uid_gid_boundaries_body() {
 		cat ${HOME}/foo.conf
 }
 
+atf_test_case homemode_boolean_no_crash
+homemode_boolean_no_crash_head() {
+	atf_set "descr" "Verify that homemode = yes in config gives a clean error"
+}
+homemode_boolean_no_crash_body() {
+	echo 'homemode = yes' > ${HOME}/bad.conf
+	populate_etc_skel
+	atf_check -s exit:1 -e inline:"pw: Invalid mode: 'yes'\n" \
+		${PW} useradd -D -C ${HOME}/bad.conf
+}
+
 atf_init_test_cases() {
 	atf_add_test_case generate_config
 	atf_add_test_case modify_config_uid_gid_boundaries
+	atf_add_test_case homemode_boolean_no_crash
 }