[PATCH 5.15 071/148] ipvlan: Fix out-of-bound bugs caused by unset skb->mac_header

Greg Kroah-Hartman
2022-09-26T11:16:54Z

From: Lu Wei <luwei32@huawei.com>

[ Upstream commit 81225b2ea161af48e093f58e8dfee6d705b16af4 ]

If an AF_PACKET socket is used to send packets through ipvlan and the
default xmit function of the AF_PACKET socket is changed from
dev_queue_xmit() to packet_direct_xmit() via setsockopt() with the option
name of PACKET_QDISC_BYPASS, the skb->mac_header may not be reset and
remains as the initial value of 65535, this may trigger slab-out-of-bounds
bugs as following:

=================================================================
UG: KASAN: slab-out-of-bounds in ipvlan_xmit_mode_l2+0xdb/0x330 [ipvlan]
PU: 2 PID: 1768 Comm: raw_send Kdump: loaded Not tainted 6.0.0-rc4+ #6
ardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.14.0-1.fc33
all Trace:
print_address_description.constprop.0+0x1d/0x160
print_report.cold+0x4f/0x112
kasan_report+0xa3/0x130
ipvlan_xmit_mode_l2+0xdb/0x330 [ipvlan]
ipvlan_start_xmit+0x29/0xa0 [ipvlan]
__dev_direct_xmit+0x2e2/0x380
packet_direct_xmit+0x22/0x60
packet_snd+0x7c9/0xc40
sock_sendmsg+0x9a/0xa0
__sys_sendto+0x18a/0x230
__x64_sys_sendto+0x74/0x90
do_syscall_64+0x3b/0x90
entry_SYSCALL_64_after_hwframe+0x63/0xcd

The root cause is:
1. packet_snd() only reset skb->mac_header when sock->type is SOCK_RAW
and skb->protocol is not specified as in packet_parse_headers()

2. packet_direct_xmit() doesn't reset skb->mac_header as dev_queue_xmit()

In this case, skb->mac_header is 65535 when ipvlan_xmit_mode_l2() is
called. So when ipvlan_xmit_mode_l2() gets mac header with eth_hdr() which
use "skb->head + skb->mac_header", out-of-bound access occurs.

This patch replaces eth_hdr() with skb_eth_hdr() in ipvlan_xmit_mode_l2()
and reset mac header in multicast to solve this out-of-bound bug.

Fixes: 2ad7bf363841 ("ipvlan: Initial check-in of the IPVLAN driver.")
Signed-off-by: Lu Wei <luwei32@huawei.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/net/ipvlan/ipvlan_core.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ipvlan/ipvlan_core.c b/drivers/net/ipvlan/ipvlan_core.c
index 6cd50106e611..d7fb6302d699 100644
--- a/drivers/net/ipvlan/ipvlan_core.c
+++ b/drivers/net/ipvlan/ipvlan_core.c
@@ -496,7 +496,6 @@ static int ipvlan_process_v6_outbound(struct sk_buff *skb)

static int ipvlan_process_outbound(struct sk_buff *skb)
{
- struct ethhdr *ethh = eth_hdr(skb);
int ret = NET_XMIT_DROP;

/* The ipvlan is a pseudo-L2 device, so the packets that we receive
@@ -506,6 +505,8 @@ static int ipvlan_process_outbound(struct sk_buff *skb)
if (skb_mac_header_was_set(skb)) {
/* In this mode we dont care about
* multicast and broadcast traffic */
+ struct ethhdr *ethh = eth_hdr(skb);
+
if (is_multicast_ether_addr(ethh->h_dest)) {
pr_debug_ratelimited(
"Dropped {multi|broad}cast of type=[%x]\n",
@@ -590,7 +591,7 @@ static int ipvlan_xmit_mode_l3(struct sk_buff *skb, struct net_device *dev)
static int ipvlan_xmit_mode_l2(struct sk_buff *skb, struct net_device *dev)
{
const struct ipvl_dev *ipvlan = netdev_priv(dev);
- struct ethhdr *eth = eth_hdr(skb);
+ struct ethhdr *eth = skb_eth_hdr(skb);
struct ipvl_addr *addr;
void *lyr3h;
int addr_type;
@@ -620,6 +621,7 @@ static int ipvlan_xmit_mode_l2(struct sk_buff *skb, struct net_device *dev)
return dev_forward_skb(ipvlan->phy_dev, skb);

} else if (is_multicast_ether_addr(eth->h_dest)) {
+ skb_reset_mac_header(skb);
ipvlan_skb_crossing_ns(skb, NULL);
ipvlan_multicast_enqueue(ipvlan->port, skb, true);
return NET_XMIT_SUCCESS;
--
2.35.1