blob: 85573c6b1c071635e4a9eb258e68d9bc9fc03650 [file] [log] [blame]
From ccb4556bd073e575abe23041b1c3f4f71009f677 Mon Sep 17 00:00:00 2001
From: Or Cohen <orcohen@paloaltonetworks.com>
Date: Thu, 3 Sep 2020 21:05:28 -0700
Subject: [PATCH] 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: 8913336a7e8d ("packet: add PACKET_RESERVE sockopt")
Signed-off-by: Or Cohen <orcohen@paloaltonetworks.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index bba78d238631..b2e4c4b192e6 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -2168,7 +2168,8 @@ static int tpacket_rcv(struct sk_buff *skb, struct net_device *dev,
int skb_len = skb->len;
unsigned int snaplen, res;
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 timespec ts;
__u32 ts_status;
@@ -2237,6 +2238,10 @@ static int tpacket_rcv(struct sk_buff *skb, struct net_device *dev,
}
macoff = netoff - maclen;
}
+ if (netoff > USHRT_MAX) {
+ atomic_inc(&po->tp_drops);
+ goto drop_n_restore;
+ }
if (po->tp_version <= TPACKET_V2) {
if (macoff + snaplen > po->rx_ring.frame_size) {
if (po->copy_thresh &&
--
2.27.0