From: Guillaume Nault <gnault@redhat.com>
To: David Miller <davem@davemloft.net>, Jakub Kicinski <kuba@kernel.org>
Cc: netdev@vger.kernel.org,
Martin Varghese <martin.varghese@nokia.com>,
Willem de Bruijn <willemb@google.com>
Subject: [PATCH net] bareudp: Fix invalid read beyond skb's linear data
Date: Fri, 6 Aug 2021 17:52:06 +0200 [thread overview]
Message-ID: <7741c46545c6ef02e70c80a9b32814b22d9616b3.1628264975.git.gnault@redhat.com> (raw)
Data beyond the UDP header might not be part of the skb's linear data.
Use skb_copy_bits() instead of direct access to skb->data+X, so that
we read the correct bytes even on a fragmented skb.
Fixes: 4b5f67232d95 ("net: Special handling for IP & MPLS.")
Signed-off-by: Guillaume Nault <gnault@redhat.com>
---
drivers/net/bareudp.c | 16 +++++++++++-----
1 file changed, 11 insertions(+), 5 deletions(-)
diff --git a/drivers/net/bareudp.c b/drivers/net/bareudp.c
index a7ee0af1af90..54e321a695ce 100644
--- a/drivers/net/bareudp.c
+++ b/drivers/net/bareudp.c
@@ -71,12 +71,18 @@ static int bareudp_udp_encap_recv(struct sock *sk, struct sk_buff *skb)
family = AF_INET6;
if (bareudp->ethertype == htons(ETH_P_IP)) {
- struct iphdr *iphdr;
+ __u8 ipversion;
- iphdr = (struct iphdr *)(skb->data + BAREUDP_BASE_HLEN);
- if (iphdr->version == 4) {
- proto = bareudp->ethertype;
- } else if (bareudp->multi_proto_mode && (iphdr->version == 6)) {
+ if (skb_copy_bits(skb, BAREUDP_BASE_HLEN, &ipversion,
+ sizeof(ipversion))) {
+ bareudp->dev->stats.rx_dropped++;
+ goto drop;
+ }
+ ipversion >>= 4;
+
+ if (ipversion == 4) {
+ proto = htons(ETH_P_IP);
+ } else if (ipversion == 6 && bareudp->multi_proto_mode) {
proto = htons(ETH_P_IPV6);
} else {
bareudp->dev->stats.rx_dropped++;
--
2.21.3
next reply other threads:[~2021-08-06 15:52 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-06 15:52 Guillaume Nault [this message]
2021-08-06 23:22 ` [PATCH net] bareudp: Fix invalid read beyond skb's linear data Jakub Kicinski
2021-08-08 16:16 ` Guillaume Nault
2021-08-09 16:19 ` Jakub Kicinski
2021-08-10 9:33 ` Guillaume Nault
2021-08-09 22:40 ` patchwork-bot+netdevbpf
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