From: Guillaume Nault <gnault@redhat.com>
Date: Fri, 6 Aug 2021 17:52:06 +0200
Subject: bareudp: Fix invalid read beyond skb's linear data
Patch-mainline: v5.14-rc6
Git-commit: 143a8526ab5fd4f8a0c4fe2a9cb28c181dc5a95f
References: jsc#SLE-15172
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>
Link: https://lore.kernel.org/r/7741c46545c6ef02e70c80a9b32814b22d9616b3.1628264975.git.gnault@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
drivers/net/bareudp.c | 16 +++++++++++-----
1 file changed, 11 insertions(+), 5 deletions(-)
--- a/drivers/net/bareudp.c
+++ b/drivers/net/bareudp.c
@@ -72,12 +72,18 @@ static int bareudp_udp_encap_recv(struct
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++;