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Subject[PATCH 5.3 082/140] erspan: fix the tun_info options_len check for erspan
Date
From: Xin Long <lucien.xin@gmail.com>

[ Upstream commit 2eb8d6d2910cfe3dc67dc056f26f3dd9c63d47cd ]

The check for !md doens't really work for ip_tunnel_info_opts(info) which
only does info + 1. Also to avoid out-of-bounds access on info, it should
ensure options_len is not less than erspan_metadata in both erspan_xmit()
and ip6erspan_tunnel_xmit().

Fixes: 1a66a836da ("gre: add collect_md mode to ERSPAN tunnel")
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/ipv4/ip_gre.c | 4 ++--
net/ipv6/ip6_gre.c | 4 ++--
2 files changed, 4 insertions(+), 4 deletions(-)

--- a/net/ipv4/ip_gre.c
+++ b/net/ipv4/ip_gre.c
@@ -509,9 +509,9 @@ static void erspan_fb_xmit(struct sk_buf
key = &tun_info->key;
if (!(tun_info->key.tun_flags & TUNNEL_ERSPAN_OPT))
goto err_free_skb;
- md = ip_tunnel_info_opts(tun_info);
- if (!md)
+ if (tun_info->options_len < sizeof(*md))
goto err_free_skb;
+ md = ip_tunnel_info_opts(tun_info);

/* ERSPAN has fixed 8 byte GRE header */
version = md->version;
--- a/net/ipv6/ip6_gre.c
+++ b/net/ipv6/ip6_gre.c
@@ -980,9 +980,9 @@ static netdev_tx_t ip6erspan_tunnel_xmit
dsfield = key->tos;
if (!(tun_info->key.tun_flags & TUNNEL_ERSPAN_OPT))
goto tx_err;
- md = ip_tunnel_info_opts(tun_info);
- if (!md)
+ if (tun_info->options_len < sizeof(*md))
goto tx_err;
+ md = ip_tunnel_info_opts(tun_info);

tun_id = tunnel_id_to_key32(key->tun_id);
if (md->version == 1) {

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