Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 1c3886dc authored by Or Cohen's avatar Or Cohen Committed by Greg Kroah-Hartman
Browse files

net/packet: fix overflow in tpacket_rcv 



commit acf69c946233259ab4d64f8869d4037a198c7f06 upstream.

Using tp_reserve to calculate netoff can overflow as
tp_reserve is unsigned int and netoff is unsigned short.

This may lead to macoff receving a smaller value then
sizeof(struct virtio_net_hdr), and if po->has_vnet_hdr
is set, an out-of-bounds write will occur when
calling virtio_net_hdr_from_skb.

The bug is fixed by converting netoff to unsigned int
and checking if it exceeds USHRT_MAX.

This addresses CVE-2020-14386

Fixes: 8913336a ("packet: add PACKET_RESERVE sockopt")
Signed-off-by: default avatarOr Cohen <orcohen@paloaltonetworks.com>
Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
[ snu: backported to pre-5.3, changed tp_drops counting/locking ]
Signed-off-by: default avatarStefan Nuernberger <snu@amazon.com>
CC: David Woodhouse <dwmw@amazon.co.uk>
CC: Amit Shah <aams@amazon.com>
CC: stable@vger.kernel.org
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent b6f69f72

net/packet/af_packet.c

+8 −1
Original line number Original line Diff line number Diff line
@@ -2162,7 +2162,8 @@ static int tpacket_rcv(struct sk_buff *skb, struct net_device *dev, 
	int skb_len = skb->len;

	int skb_len = skb->len;

	unsigned int snaplen, res;

	unsigned int snaplen, res;

	unsigned long status = TP_STATUS_USER;

	unsigned long status = TP_STATUS_USER;

	unsigned short macoff, netoff, hdrlen;

	unsigned short macoff, hdrlen;

	unsigned int netoff;

	struct sk_buff *copy_skb = NULL;

	struct sk_buff *copy_skb = NULL;

	struct timespec ts;

	struct timespec ts;

	__u32 ts_status;

	__u32 ts_status;
@@ -2225,6 +2226,12 @@ static int tpacket_rcv(struct sk_buff *skb, struct net_device *dev, 
		}

		}

		macoff = netoff - maclen;

		macoff = netoff - maclen;

	}

	}

	if (netoff > USHRT_MAX) {

		spin_lock(&sk->sk_receive_queue.lock);

		po->stats.stats1.tp_drops++;

		spin_unlock(&sk->sk_receive_queue.lock);

		goto drop_n_restore;

	}

	if (po->tp_version <= TPACKET_V2) {

	if (po->tp_version <= TPACKET_V2) {

		if (macoff + snaplen > po->rx_ring.frame_size) {

		if (macoff + snaplen > po->rx_ring.frame_size) {

			if (po->copy_thresh &&

			if (po->copy_thresh &&