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From: Steffen Klassert <steffen.klassert@secunet•com>
To: David Miller <davem@davemloft•net>
Cc: Herbert Xu <herbert@gondor•apana.org.au>,
	Steffen Klassert <steffen.klassert@secunet•com>,
	<netdev@vger•kernel.org>
Subject: [PATCH 09/15] xfrm: call xfrm_output_gso when inner_protocol is set in xfrm_output
Date: Fri, 29 May 2020 13:04:02 +0200	[thread overview]
Message-ID: <20200529110408.6349-10-steffen.klassert@secunet.com> (raw)
In-Reply-To: <20200529110408.6349-1-steffen.klassert@secunet.com>

From: Xin Long <lucien.xin@gmail•com>

An use-after-free crash can be triggered when sending big packets over
vxlan over esp with esp offload enabled:

  [] BUG: KASAN: use-after-free in ipv6_gso_pull_exthdrs.part.8+0x32c/0x4e0
  [] Call Trace:
  []  dump_stack+0x75/0xa0
  []  kasan_report+0x37/0x50
  []  ipv6_gso_pull_exthdrs.part.8+0x32c/0x4e0
  []  ipv6_gso_segment+0x2c8/0x13c0
  []  skb_mac_gso_segment+0x1cb/0x420
  []  skb_udp_tunnel_segment+0x6b5/0x1c90
  []  inet_gso_segment+0x440/0x1380
  []  skb_mac_gso_segment+0x1cb/0x420
  []  esp4_gso_segment+0xae8/0x1709 [esp4_offload]
  []  inet_gso_segment+0x440/0x1380
  []  skb_mac_gso_segment+0x1cb/0x420
  []  __skb_gso_segment+0x2d7/0x5f0
  []  validate_xmit_skb+0x527/0xb10
  []  __dev_queue_xmit+0x10f8/0x2320 <---
  []  ip_finish_output2+0xa2e/0x1b50
  []  ip_output+0x1a8/0x2f0
  []  xfrm_output_resume+0x110e/0x15f0
  []  __xfrm4_output+0xe1/0x1b0
  []  xfrm4_output+0xa0/0x200
  []  iptunnel_xmit+0x5a7/0x920
  []  vxlan_xmit_one+0x1658/0x37a0 [vxlan]
  []  vxlan_xmit+0x5e4/0x3ec8 [vxlan]
  []  dev_hard_start_xmit+0x125/0x540
  []  __dev_queue_xmit+0x17bd/0x2320  <---
  []  ip6_finish_output2+0xb20/0x1b80
  []  ip6_output+0x1b3/0x390
  []  ip6_xmit+0xb82/0x17e0
  []  inet6_csk_xmit+0x225/0x3d0
  []  __tcp_transmit_skb+0x1763/0x3520
  []  tcp_write_xmit+0xd64/0x5fe0
  []  __tcp_push_pending_frames+0x8c/0x320
  []  tcp_sendmsg_locked+0x2245/0x3500
  []  tcp_sendmsg+0x27/0x40

As on the tx path of vxlan over esp, skb->inner_network_header would be
set on vxlan_xmit() and xfrm4_tunnel_encap_add(), and the later one can
overwrite the former one. It causes skb_udp_tunnel_segment() to use a
wrong skb->inner_network_header, then the issue occurs.

This patch is to fix it by calling xfrm_output_gso() instead when the
inner_protocol is set, in which gso_segment of inner_protocol will be
done first.

While at it, also improve some code around.

Fixes: 7862b4058b9f ("esp: Add gso handlers for esp4 and esp6")
Reported-by: Xiumei Mu <xmu@redhat•com>
Signed-off-by: Xin Long <lucien.xin@gmail•com>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet•com>
---
 net/xfrm/xfrm_output.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/net/xfrm/xfrm_output.c b/net/xfrm/xfrm_output.c
index 2fd3d990d992..69c33cab8f49 100644
--- a/net/xfrm/xfrm_output.c
+++ b/net/xfrm/xfrm_output.c
@@ -583,18 +583,20 @@ int xfrm_output(struct sock *sk, struct sk_buff *skb)
 		xfrm_state_hold(x);
 
 		if (skb_is_gso(skb)) {
-			skb_shinfo(skb)->gso_type |= SKB_GSO_ESP;
+			if (skb->inner_protocol)
+				return xfrm_output_gso(net, sk, skb);
 
-			return xfrm_output2(net, sk, skb);
+			skb_shinfo(skb)->gso_type |= SKB_GSO_ESP;
+			goto out;
 		}
 
 		if (x->xso.dev && x->xso.dev->features & NETIF_F_HW_ESP_TX_CSUM)
 			goto out;
+	} else {
+		if (skb_is_gso(skb))
+			return xfrm_output_gso(net, sk, skb);
 	}
 
-	if (skb_is_gso(skb))
-		return xfrm_output_gso(net, sk, skb);
-
 	if (skb->ip_summed == CHECKSUM_PARTIAL) {
 		err = skb_checksum_help(skb);
 		if (err) {
-- 
2.17.1


  parent reply	other threads:[~2020-05-29 11:04 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-29 11:03 pull request (net): ipsec 2020-05-29 Steffen Klassert
2020-05-29 11:03 ` [PATCH 01/15] xfrm: allow to accept packets with ipv6 NEXTHDR_HOP in xfrm_input Steffen Klassert
2020-05-29 11:03 ` [PATCH 02/15] xfrm: do pskb_pull properly in __xfrm_transport_prep Steffen Klassert
2020-05-29 11:03 ` [PATCH 03/15] esp6: get the right proto for transport mode in esp6_gso_encap Steffen Klassert
2020-05-29 11:03 ` [PATCH 04/15] xfrm: remove the xfrm_state_put call becofe going to out_reset Steffen Klassert
2020-05-29 11:03 ` [PATCH 05/15] xfrm: fix error in comment Steffen Klassert
2020-05-29 11:03 ` [PATCH 06/15] xfrm: espintcp: save and call old ->sk_destruct Steffen Klassert
2020-05-29 11:04 ` [PATCH 07/15] esp6: support ipv6 nexthdrs process for beet gso segment Steffen Klassert
2020-05-29 11:04 ` [PATCH 08/15] esp4: " Steffen Klassert
2020-05-29 11:04 ` Steffen Klassert [this message]
2020-05-29 11:04 ` [PATCH 10/15] ip_vti: receive ipip packet by calling ip_tunnel_rcv Steffen Klassert
2020-05-29 11:04 ` [PATCH 11/15] xfrm interface: fix oops when deleting a x-netns interface Steffen Klassert
2020-05-29 11:04 ` [PATCH 12/15] esp6: calculate transport_header correctly when sel.family != AF_INET6 Steffen Klassert
2020-05-29 11:04 ` [PATCH 13/15] esp4: improve xfrm4_beet_gso_segment() to be more readable Steffen Klassert
2020-05-29 11:04 ` [PATCH 14/15] xfrm: fix a warning in xfrm_policy_insert_list Steffen Klassert
2020-05-29 11:04 ` [PATCH 15/15] xfrm: fix a NULL-ptr deref in xfrm_local_error Steffen Klassert
2020-05-29 20:06 ` pull request (net): ipsec 2020-05-29 David Miller

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