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Date:      Fri, 25 Jan 2019 15:46:30 +0000 (UTC)
From:      Michael Tuexen <tuexen@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-12@freebsd.org
Subject:   svn commit: r343436 - stable/12/sys/netinet
Message-ID:  <201901251546.x0PFkUHT052251@repo.freebsd.org>
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Author: tuexen
Date: Fri Jan 25 15:46:30 2019
New Revision: 343436
URL: https://svnweb.freebsd.org/changeset/base/343436

Log:
  MFC r343089:
  
  Limit the user-controllable amount of memory the kernel allocates
  via IPPROTO_SCTP level socket options.
  
  This issue was found by running syzkaller.

Modified:
  stable/12/sys/netinet/sctp_constants.h
  stable/12/sys/netinet/sctp_usrreq.c
Directory Properties:
  stable/12/   (props changed)

Modified: stable/12/sys/netinet/sctp_constants.h
==============================================================================
--- stable/12/sys/netinet/sctp_constants.h	Fri Jan 25 15:44:53 2019	(r343435)
+++ stable/12/sys/netinet/sctp_constants.h	Fri Jan 25 15:46:30 2019	(r343436)
@@ -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: stable/12/sys/netinet/sctp_usrreq.c
==============================================================================
--- stable/12/sys/netinet/sctp_usrreq.c	Fri Jan 25 15:44:53 2019	(r343435)
+++ stable/12/sys/netinet/sctp_usrreq.c	Fri Jan 25 15:46:30 2019	(r343436)
@@ -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) {

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