if_ovpn: fix use-after-free

ovpn_encrypt_tx_cb() calls ovpn_encap() to transmit a packet, then adds
the length of the packet to the "tunnel_bytes_sent" counter.  However,
after ovpn_encap() returns 0, the mbuf chain may have been freed, so the
load of m->m_pkthdr.len may be a use-after-free.

Reported by:	markj
Sponsored by:	Rubicon Communications, LLC ("Netgate")

This commit is contained in:

Kristof Provost

2022-10-17 09:24:41 +02:00

parent 865f46b255

commit b136983a8a

1 changed files with 3 additions and 2 deletions

									
										sys/net/if_ovpn.c
									
		+3
		-2
	
												View File
												
				@@ -1382,6 +1382,7 @@ ovpn_encrypt_tx_cb(struct cryptop *crp)

					struct ovpn_kpeer *peer = crp->crp_opaque;

					struct ovpn_softc *sc = peer->sc;

					struct mbuf *m = crp->crp_buf.cb_mbuf;

					int tunnel_len;

					int ret;

					if (crp->crp_etype != 0) {

				@@ -1397,11 +1398,11 @@ ovpn_encrypt_tx_cb(struct cryptop *crp)

					MPASS(crp->crp_buf.cb_type == CRYPTO_BUF_MBUF);

					tunnel_len = m->m_pkthdr.len - sizeof(struct ovpn_wire_header);

					ret = ovpn_encap(sc, peer->peerid, m);

					if (ret == 0) {

						OVPN_COUNTER_ADD(sc, sent_data_pkts, 1);

						OVPN_COUNTER_ADD(sc, tunnel_bytes_sent, m->m_pkthdr.len -

						    sizeof(struct ovpn_wire_header));

						OVPN_COUNTER_ADD(sc, tunnel_bytes_sent, tunnel_len);

					}

					CURVNET_RESTORE();