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backport overflow fix for net/packet receive handling

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Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>
This commit is contained in:
Thomas Lamprecht 2020-09-04 10:21:46 +02:00
parent 181693ca72
commit 861cb4ecb1
1 changed files with 48 additions and 0 deletions
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48
patches/kernel/0007-net-packet-fix-overflow-in-tpacket_rcv.patch Normal file
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@ -0,0 +1,48 @@
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Or Cohen <orcohen@paloaltonetworks.com>
Date: Sun, 30 Aug 2020 20:04:51 +0300
Subject: [PATCH] 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.
Fixes: 8913336a7e8d ("packet: add PACKET_RESERVE sockopt")
Signed-off-by: Or Cohen <orcohen@paloaltonetworks.com>
Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>
---
net/packet/af_packet.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index 7735340c892e..fbc2d4dfddf0 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -2169,7 +2169,8 @@ 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;
@@ -2238,6 +2239,10 @@ 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 &&