Fix possible segfault in check_ntp_peer with deliberately invalid packets

git-svn-id: https://nagiosplug.svn.sourceforge.net/svnroot/nagiosplug/nagiosplug/trunk@2052 f882894a-f735-0410-b71e-b25c423dba1c

1 files changed, 3 insertions, 0 deletions

diff --git a/plugins/check_ntp_peer.c b/plugins/check_ntp_peer.c
index 72cec63..6a4401c 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.