svn commit: r360746 - stable/11/sys/netinet

[Michael Tuexen]

Author: tuexen
Date: Thu May  7 02:16:25 2020
New Revision: 360746
URL: https://svnweb.freebsd.org/changeset/base/360746

Log:
  MFC r353303: Improve SCTP packet handling
  
  Validate length before use it, not vice versa.
  r353060 should have contained this...
  This fixes
  https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=18070

Modified:
  stable/11/sys/netinet/sctp_asconf.c
Directory Properties:
  stable/11/   (props changed)

Modified: stable/11/sys/netinet/sctp_asconf.c
==============================================================================
--- stable/11/sys/netinet/sctp_asconf.c	Thu May  7 02:13:28 2020	(r360745)
+++ stable/11/sys/netinet/sctp_asconf.c	Thu May  7 02:16:25 2020	(r360746)
@@ -332,11 +332,11 @@ sctp_process_asconf_delete_ip(struct sockaddr *src,
 #endif
 
 	aparam_length = ntohs(aph->ph.param_length);
-	ph = (struct sctp_paramhdr *)(aph + 1);
-	param_type = ntohs(ph->param_type);
 	if (aparam_length < sizeof(struct sctp_asconf_paramhdr) + sizeof(struct sctp_paramhdr)) {
 		return (NULL);
 	}
+	ph = (struct sctp_paramhdr *)(aph + 1);
+	param_type = ntohs(ph->param_type);
 #if defined(INET) || defined(INET6)
 	param_length = ntohs(ph->param_length);
 	if (param_length + sizeof(struct sctp_asconf_paramhdr) != aparam_length) {