2 files changed, 5 insertions, 1 deletions

diff --git a/NEWS b/NEWS
index cb68df66..ab597d4d 100644
--- a/NEWS
+++ b/NEWS
@@ -11,7 +11,8 @@ This file documents the major additions and syntax changes between releases.
         check_icmp now supports packet size modification
         check_http -e now accepts a comma-delimited list of expected status codes
         libtap now included with this distribution for easier testing. Run ./configure with --enable-libtap
-        check_ntp_peer/check_ntp_time used to show port in --help but ignored the argument - now implemented.
+        check_ntp_peer/check_ntp_time used to show port in --help but ignored the argument - now implemented
+        Fix possible segfault in check_ntp_peer with deliberately invalid packets
 
 1.4.12 27th May 2008
         Added ./check_nt -v INSTANCES to count number of instances (Alessandro Ren)
diff --git a/plugins/check_ntp_peer.c b/plugins/check_ntp_peer.c
index 72cec639..6a4401ca 100644
--- a/plugins/check_ntp_peer.c
+++ b/plugins/check_ntp_peer.c
@@ -299,6 +299,9 @@ int ntp_request(const char *host, double *offset, int *offset_result, double *ji
                 if(read(conn, &req, SIZEOF_NTPCM(req)) == -1)
                         die(STATE_CRITICAL, "NTP CRITICAL: No response from NTP server\n");
                 DBG(print_ntp_control_message(&req));
+                /* discard obviously invalid packets */
+                if (ntohs(req.count) > MAX_CM_SIZE)
+                        die(STATE_CRITICAL, "NTP CRITICAL: Invalid paclet received from NTP server\n");
                 if (LI(req.flags) == LI_ALARM) li_alarm = 1;
                 /* Each peer identifier is 4 bytes in the data section, which
                  * we represent as a ntp_assoc_status_pair datatype.