svn commit: r343089 - head/sys/netinet

[Michael Tuexen]

Author: tuexen
Date: Wed Jan 16 11:33:47 2019
New Revision: 343089
URL: https://svnweb.freebsd.org/changeset/base/343089

Log:
  Limit the user-controllable amount of memory the kernel allocates
  via IPPROTO_SCTP level socket options.
  
  This issue was found by running syzkaller.
  
  MFC after:	1 week

Modified:
  head/sys/netinet/sctp_constants.h
  head/sys/netinet/sctp_usrreq.c

Modified: head/sys/netinet/sctp_constants.h
==============================================================================
--- head/sys/netinet/sctp_constants.h	Wed Jan 16 10:33:51 2019	(r343088)
+++ head/sys/netinet/sctp_constants.h	Wed Jan 16 11:33:47 2019	(r343089)
@@ -983,6 +983,9 @@ __FBSDID("$FreeBSD$");
     ((((uint8_t *)&(a)->s_addr)[0] == 169) && \
      (((uint8_t *)&(a)->s_addr)[1] == 254))
 
+/* Maximum size of optval for IPPROTO_SCTP level socket options. */
+#define SCTP_SOCKET_OPTION_LIMIT (64 * 1024)
+
 
 #if defined(_KERNEL)
 #define SCTP_GETTIME_TIMEVAL(x) (getmicrouptime(x))

Modified: head/sys/netinet/sctp_usrreq.c
==============================================================================
--- head/sys/netinet/sctp_usrreq.c	Wed Jan 16 10:33:51 2019	(r343088)
+++ head/sys/netinet/sctp_usrreq.c	Wed Jan 16 11:33:47 2019	(r343089)
@@ -6828,6 +6828,10 @@ sctp_ctloutput(struct socket *so, struct sockopt *sopt
 		return (error);
 	}
 	optsize = sopt->sopt_valsize;
+	if (optsize > SCTP_SOCKET_OPTION_LIMIT) {
+		SCTP_LTRACE_ERR_RET(so->so_pcb, NULL, NULL, SCTP_FROM_SCTP_USRREQ, ENOBUFS);
+		return (ENOBUFS);
+	}
 	if (optsize) {
 		SCTP_MALLOC(optval, void *, optsize, SCTP_M_SOCKOPT);
 		if (optval == NULL) {