From: Stefan Nuernberger <snu@amazon.com>
To: <carnil@debian.org>
Cc: <aams@amazon.de>, <dwmw@amazon.co.uk>, <edumazet@google.com>,
<gregkh@linuxfoundation.org>, <netdev@vger.kernel.org>,
<orcohen@paloaltonetworks.com>, <snu@amazon.de>,
<stable@vger.kernel.org>, Stefan Nuernberger <snu@amazon.com>,
Amit Shah <aams@amazon.com>
Subject: [PATCH] net/packet: fix overflow in tpacket_rcv
Date: Mon, 21 Sep 2020 19:02:50 +0200 [thread overview]
Message-ID: <20200921170250.28535-1-snu@amazon.com> (raw)
In-Reply-To: <20200905065422.GA556394@eldamar.local>
From: Or Cohen <orcohen@paloaltonetworks.com>
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>
[ snu: backported to pre-5.3, changed tp_drops counting/locking ]
Signed-off-by: Stefan Nuernberger <snu@amazon.com>
CC: David Woodhouse <dwmw@amazon.co.uk>
CC: Amit Shah <aams@amazon.com>
CC: stable@vger.kernel.org
---
net/packet/af_packet.c | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index fb643945e424..b5b79f501541 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -2161,7 +2161,8 @@ 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;
@@ -2223,6 +2224,12 @@ static int tpacket_rcv(struct sk_buff *skb, struct net_device *dev,
}
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 (macoff + snaplen > po->rx_ring.frame_size) {
if (po->copy_thresh &&
--
2.28.0
Amazon Development Center Germany GmbH
Krausenstr. 38
10117 Berlin
Geschaeftsfuehrung: Christian Schlaeger, Jonathan Weiss
Eingetragen am Amtsgericht Charlottenburg unter HRB 149173 B
Sitz: Berlin
Ust-ID: DE 289 237 879
prev parent reply other threads:[~2020-09-21 17:05 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-03 17:07 Vulnerability report - af_packet.c - CVE-2020-14386 Or Cohen
2020-09-04 13:30 ` [PATCH] net/packet: fix overflow in tpacket_rcv Stefan Nuernberger
2020-09-04 14:16 ` Greg Kroah-Hartman
2020-09-04 14:22 ` Nuernberger, Stefan
2020-09-04 14:36 ` gregkh
2020-09-05 6:54 ` Salvatore Bonaccorso
2020-09-21 17:02 ` Stefan Nuernberger [this message]
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