From: Taehee Yoo <ap420073@xxxxxxxxx>
commit 67a9c94317402b826fc3db32afc8f39336803d97 upstream.
skb_tunnel_info() returns pointer of lwtstate->data as ip_tunnel_info
type without validation. lwtstate->data can have various types such as
mpls_iptunnel_encap, etc and these are not compatible.
So skb_tunnel_info() should validate before returning that pointer.
Splat looks like:
BUG: KASAN: slab-out-of-bounds in vxlan_get_route+0x418/0x4b0 [vxlan]
Read of size 2 at addr ffff888106ec2698 by task ping/811
CPU: 1 PID: 811 Comm: ping Not tainted 5.13.0+ #1195
Call Trace:
dump_stack_lvl+0x56/0x7b
print_address_description.constprop.8.cold.13+0x13/0x2ee
? vxlan_get_route+0x418/0x4b0 [vxlan]
? vxlan_get_route+0x418/0x4b0 [vxlan]
kasan_report.cold.14+0x83/0xdf
? vxlan_get_route+0x418/0x4b0 [vxlan]
vxlan_get_route+0x418/0x4b0 [vxlan]
[ ... ]
vxlan_xmit_one+0x148b/0x32b0 [vxlan]
[ ... ]
vxlan_xmit+0x25c5/0x4780 [vxlan]
[ ... ]
dev_hard_start_xmit+0x1ae/0x6e0
__dev_queue_xmit+0x1f39/0x31a0
[ ... ]
neigh_xmit+0x2f9/0x940
mpls_xmit+0x911/0x1600 [mpls_iptunnel]
lwtunnel_xmit+0x18f/0x450
ip_finish_output2+0x867/0x2040
[ ... ]
Fixes: 61adedf3e3f1 ("route: move lwtunnel state to dst_entry")
Signed-off-by: Taehee Yoo <ap420073@xxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
include/net/dst_metadata.h | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
--- a/include/net/dst_metadata.h
+++ b/include/net/dst_metadata.h
@@ -45,7 +45,9 @@ skb_tunnel_info(const struct sk_buff *sk
return &md_dst->u.tun_info;
dst = skb_dst(skb);
- if (dst && dst->lwtstate)
+ if (dst && dst->lwtstate &&
+ (dst->lwtstate->type == LWTUNNEL_ENCAP_IP ||
+ dst->lwtstate->type == LWTUNNEL_ENCAP_IP6))
return lwt_tun_info(dst->lwtstate);
return NULL;
