Commit acf69c94 authored by Or Cohen's avatar Or Cohen Committed by Linus Torvalds

net/packet: fix overflow in tpacket_rcv

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>
parent b25d1dc9
...@@ -2170,7 +2170,8 @@ static int tpacket_rcv(struct sk_buff *skb, struct net_device *dev, ...@@ -2170,7 +2170,8 @@ 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 timespec64 ts; struct timespec64 ts;
__u32 ts_status; __u32 ts_status;
...@@ -2239,6 +2240,10 @@ static int tpacket_rcv(struct sk_buff *skb, struct net_device *dev, ...@@ -2239,6 +2240,10 @@ static int tpacket_rcv(struct sk_buff *skb, struct net_device *dev,
} }
macoff = netoff - maclen; macoff = netoff - maclen;
} }
if (netoff > USHRT_MAX) {
atomic_inc(&po->tp_drops);
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 &&
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment