[systemd-devel] [PATCH] timesyncd: consider too long packets as invalid

[Topi Miettinen]

If the received NTP message from server didn't fit to our buffer, either
it is doing something nasty or we don't know the protocol. Consider the
packet as invalid.
---
 src/timesync/timesyncd-manager.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/timesync/timesyncd-manager.c b/src/timesync/timesyncd-manager.c
index 117ea8c..e183f96 100644
--- a/src/timesync/timesyncd-manager.c
+++ b/src/timesync/timesyncd-manager.c
@@ -525,7 +525,8 @@ static int manager_receive_response(sd_event_source *source, int fd, uint32_t re
                 return manager_connect(m);
         }
 
-        if (iov.iov_len < sizeof(struct ntp_msg)) {
+        /* Too short or too long packet? */
+        if (iov.iov_len < sizeof(struct ntp_msg) || msghdr.msg_flags & MSG_TRUNC) {
                 log_warning("Invalid response from server. Disconnecting.");
                 return manager_connect(m);
         }
-- 
2.1.4