Package: isc-dhcp
Version: 4.2.4-3
Severity: normal
Tags: patch
User: ubuntu-de...@lists.ubuntu.com
Usertags: origin-ubuntu raring
Hi,
If I set "backoff_cutoff 0;", dhclient will crash with a divide-by-zero
instead of handling the case gracefully.
The attached patch fixes this problem.
Thanks,
-Kees
--
Kees Cook @debian.org
Description: setting "backoff-cutoff 0;" in dhclient.conf will cause
dhclient to divide by zero and crash. It should be handled more
gracefully.
Author: Kees Cook <k...@ubuntu.com>
Index: isc-dhcp-4.2.4/client/dhclient.c
===================================================================
--- isc-dhcp-4.2.4.orig/client/dhclient.c 2012-11-28 08:16:06.000000000 -0800
+++ isc-dhcp-4.2.4/client/dhclient.c 2012-11-28 08:34:30.051276136 -0800
@@ -1874,9 +1874,12 @@
client->interval += random() % (2 * client->interval);
/* Don't backoff past cutoff. */
- if (client->interval > client->config->backoff_cutoff)
- client->interval = (client->config->backoff_cutoff / 2)
- + (random() % client->config->backoff_cutoff);
+ if (client->interval > client->config->backoff_cutoff) {
+ client->interval = (client->config->backoff_cutoff / 2);
+ if (client->config->backoff_cutoff)
+ client->interval += (random() %
+ client->config->backoff_cutoff);
+ }
} else if (!client->interval)
client->interval = client->config->initial_interval;
@@ -2119,11 +2122,13 @@
/* Don't backoff past cutoff. */
if (client -> interval >
- client -> config -> backoff_cutoff)
+ client -> config -> backoff_cutoff) {
client -> interval =
- ((client -> config -> backoff_cutoff / 2)
- + ((random () >> 2) %
- client -> config -> backoff_cutoff));
+ (client -> config -> backoff_cutoff / 2);
+ if (client -> config -> backoff_cutoff)
+ client -> interval += ((random () >> 2) %
+ client -> config -> backoff_cutoff);
+ }
/* If the backoff would take us to the expiry time, just set the
timeout to the expiry time. */
