svn commit: r364589 - stable/12/sys/netinet

[Michael Tuexen]

Author: tuexen
Date: Sun Aug 23 23:11:53 2020
New Revision: 364589
URL: https://svnweb.freebsd.org/changeset/base/364589

Log:
  MFC r361222:
  Avoid an integer underflow.

Modified:
  stable/12/sys/netinet/sctp_asconf.c
Directory Properties:
  stable/12/   (props changed)

Modified: stable/12/sys/netinet/sctp_asconf.c
==============================================================================
--- stable/12/sys/netinet/sctp_asconf.c	Sun Aug 23 23:10:25 2020	(r364588)
+++ stable/12/sys/netinet/sctp_asconf.c	Sun Aug 23 23:11:53 2020	(r364589)
@@ -1803,9 +1803,9 @@ sctp_handle_asconf_ack(struct mbuf *m, int offset,
 		}		/* switch */
 
 		/* update remaining ASCONF-ACK message length to process */
-		ack_length -= SCTP_SIZE32(param_length);
-		if (ack_length <= 0) {
-			/* no more data in the mbuf chain */
+		if (ack_length > SCTP_SIZE32(param_length)) {
+			ack_length -= SCTP_SIZE32(param_length);
+		} else {
 			break;
 		}
 		offset += SCTP_SIZE32(param_length);