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.
HardenedBSD · Jan 25, 2019 · 58e6efc · 58e6efc
1 parent 4a9fc73
commit 58e6efc
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diff --git a/sys/netinet/sctp_constants.h b/sys/netinet/sctp_constants.h
@@ -977,6 +977,9 @@ __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))

diff --git a/sys/netinet/sctp_usrreq.c b/sys/netinet/sctp_usrreq.c
@@ -6812,6 +6812,10 @@ 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) {