From: Xin Long <lucien.xin@gmail.com>

Date: Mon, 18 Nov 2019 17:39:34 +0800

Subject: net: sched: ensure opts_len <= IP_TUNNEL_OPTS_MAX in act_tunnel_key

Patch-mainline: v5.4

Git-commit: 4f0e97d070984d487df027f163e52bb72d1713d8

References: bsc#1109837

info->options_len is 'u8' type, and when opts_len with a value >

IP_TUNNEL_OPTS_MAX, 'info->options_len = opts_len' will cast int

to u8 and set a wrong value to info->options_len.

Kernel crashed in my test when doing:

  # opts="0102:80:00800022"

  # for i in {1..99}; do opts="$opts,0102:80:00800022"; done

  # ip link add name geneve0 type geneve dstport 0 external

  # tc qdisc add dev eth0 ingress

  # tc filter add dev eth0 protocol ip parent ffff: \

       flower indev eth0 ip_proto udp action tunnel_key \

       set src_ip 10.0.99.192 dst_ip 10.0.99.193 \

       dst_port 6081 id 11 geneve_opts $opts \

       action mirred egress redirect dev geneve0

So we should do the similar check as cls_flower does, return error

when opts_len > IP_TUNNEL_OPTS_MAX in tunnel_key_copy_opts().

Fixes: 0ed5269f9e41 ("net/sched: add tunnel option support to act_tunnel_key")

Signed-off-by: Xin Long <lucien.xin@gmail.com>

Reviewed-by: Simon Horman <simon.horman@netronome.com>

Signed-off-by: David S. Miller <davem@davemloft.net>

Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>

---

 net/sched/act_tunnel_key.c |    4 ++++

 1 file changed, 4 insertions(+)

--- a/net/sched/act_tunnel_key.c

+++ b/net/sched/act_tunnel_key.c

@@ -137,6 +137,10 @@ static int tunnel_key_copy_opts(const st

 			if (opt_len < 0)

 				return opt_len;

 			opts_len += opt_len;

+			if (opts_len > IP_TUNNEL_OPTS_MAX) {

+				NL_SET_ERR_MSG(extack, "Tunnel options exceeds max size");

+				return -EINVAL;

+			}

 			if (dst) {

 				dst_len -= opt_len;

 				dst += opt_len;