The commit is pushed to "branch-rh7-3.10.0-1160.41.1.vz7.183.x-ovz" and will
appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh7-3.10.0-1160.41.1.vz7.183.3
------>
commit 54a2223f8be9a40306eb3f2b5ede9a9748ffa737
Author: Vasily Averin <[email protected]>
Date: Tue Sep 14 09:56:15 2021 +0300
ms/ipv6: allocate enough headroom in ip6_finish_output2()
When TEE target mirrors traffic to another interface, sk_buff may
not have enough headroom to be processed correctly.
ip_finish_output2() detect this situation for ipv4 and allocates
new skb with enogh headroom. However ipv6 lacks this logic in
ip_finish_output2 and it leads to skb_under_panic:
skbuff: skb_under_panic: text:ffffffffc0866ad4 len:96 put:24
head:ffff97be85e31800 data:ffff97be85e317f8 tail:0x58 end:0xc0 dev:gre0
------------[ cut here ]------------
kernel BUG at net/core/skbuff.c:110!
invalid opcode: 0000 [#1] SMP PTI
CPU: 2 PID: 393 Comm: kworker/2:2 Tainted: G OE 5.13.0 #13
Hardware name: Virtuozzo KVM, BIOS 1.11.0-2.vz7.4 04/01/2014
Workqueue: ipv6_addrconf addrconf_dad_work
RIP: 0010:skb_panic+0x48/0x4a
Call Trace:
skb_push.cold.111+0x10/0x10
ipgre_header+0x24/0xf0 [ip_gre]
neigh_connected_output+0xae/0xf0
ip6_finish_output2+0x1a8/0x5a0
ip6_output+0x5c/0x110
nf_dup_ipv6+0x158/0x1000 [nf_dup_ipv6]
tee_tg6+0x2e/0x40 [xt_TEE]
ip6t_do_table+0x294/0x470 [ip6_tables]
nf_hook_slow+0x44/0xc0
nf_hook.constprop.34+0x72/0xe0
ndisc_send_skb+0x20d/0x2e0
ndisc_send_ns+0xd1/0x210
addrconf_dad_work+0x3c8/0x540
process_one_work+0x1d1/0x370
worker_thread+0x30/0x390
kthread+0x116/0x130
ret_from_fork+0x22/0x30
[backport of first version of upstream patch,
patch version included finally to upstream requires some other changes]
Link: https://lkml.org/lkml/2021/7/7/469
https://jira.sw.ru/browse/PSBM-130907
Signed-off-by: Vasily Averin <[email protected]>
---
net/ipv6/ip6_output.c | 15 +++++++++++++++
1 file changed, 15 insertions(+)
diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index ca42e2c..6c2082d 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -60,6 +60,7 @@ static int ip6_finish_output2(struct sock *sk, struct sk_buff
*skb)
{
struct dst_entry *dst = skb_dst(skb);
struct net_device *dev = dst->dev;
+ unsigned int hh_len = LL_RESERVED_SPACE(dev);
const struct in6_addr *nexthop;
struct neighbour *neigh;
int ret;
@@ -67,6 +68,20 @@ static int ip6_finish_output2(struct sock *sk, struct
sk_buff *skb)
skb->protocol = htons(ETH_P_IPV6);
skb->dev = dev;
+ /* Be paranoid, rather than too clever. */
+ if (unlikely(skb_headroom(skb) < hh_len && dev->header_ops)) {
+ struct sk_buff *skb2;
+
+ skb2 = skb_realloc_headroom(skb, hh_len);
+ if (skb2 == NULL) {
+ kfree_skb(skb);
+ return -ENOMEM;
+ }
+ if (skb->sk)
+ skb_set_owner_w(skb2, skb->sk);
+ consume_skb(skb);
+ skb = skb2;
+ }
if (ipv6_addr_is_multicast(&ipv6_hdr(skb)->daddr)) {
struct inet6_dev *idev = ip6_dst_idev(skb_dst(skb));
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