Since we can feed localtime(3) with garbage input, or with input it cannot

interpret, we always need to check its return value, and in the case it's NULL
then error and exit before proceeding further otherwise in this specific
program we would find a null dereference down the road which would make the
program segfault.

OK cheloha@

diff --git a/usr.sbin/ac/ac.c b/usr.sbin/ac/ac.c
index 97d0f82..f0005ce 100644 (file)
--- a/usr.sbin/ac/ac.c
+++ b/usr.sbin/ac/ac.c
@@ -410,6 +410,8 @@ ac(FILE     *fp)
                prev = usr.ut_time;
                if (Flags & AC_D) {
                        ltm = localtime(&usr.ut_time);
+                       if (ltm == NULL)
+                               err(1, "localtime");
                        if (day >= 0 && day != ltm->tm_yday) {
                                day = ltm->tm_yday;
                                /*
@@ -461,6 +463,8 @@ ac(FILE     *fp)
 
        if (Flags & AC_D) {
                ltm = localtime(&usr.ut_time);
+               if (ltm == NULL)
+                       err(1, "localtime");
                if (day >= 0 && day != ltm->tm_yday) {
                        /*
                         * print yesterday's total