this patch is incomplete, and requires following fixup https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...
Please backport it too.
Thank you, Vasily Averin
On 7/23/21 6:57 AM, Sasha Levin wrote:
From: Vasily Averin vvs@virtuozzo.com
[ Upstream commit 5796015fa968a3349027a27dcd04c71d95c53ba5 ]
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
Signed-off-by: Vasily Averin vvs@virtuozzo.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Sasha Levin sashal@kernel.org
net/ipv6/ip6_output.c | 28 ++++++++++++++++++++++++++++ 1 file changed, 28 insertions(+)
diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c index ff4f9ebcf7f6..0efcb9b04151 100644 --- a/net/ipv6/ip6_output.c +++ b/net/ipv6/ip6_output.c @@ -60,10 +60,38 @@ static int ip6_finish_output2(struct net *net, struct sock *sk, struct sk_buff * { struct dst_entry *dst = skb_dst(skb); struct net_device *dev = dst->dev;
- unsigned int hh_len = LL_RESERVED_SPACE(dev);
- int delta = hh_len - skb_headroom(skb); const struct in6_addr *nexthop; struct neighbour *neigh; int ret;
- /* Be paranoid, rather than too clever. */
- if (unlikely(delta > 0) && dev->header_ops) {
/* pskb_expand_head() might crash, if skb is shared */if (skb_shared(skb)) {struct sk_buff *nskb = skb_clone(skb, GFP_ATOMIC);if (likely(nskb)) {if (skb->sk)skb_set_owner_w(skb, skb->sk);consume_skb(skb);} else {kfree_skb(skb);}skb = nskb;}if (skb &&pskb_expand_head(skb, SKB_DATA_ALIGN(delta), 0, GFP_ATOMIC)) {kfree_skb(skb);skb = NULL;}if (!skb) {IP6_INC_STATS(net, ip6_dst_idev(dst), IPSTATS_MIB_OUTDISCARDS);return -ENOMEM;}- }
- if (ipv6_addr_is_multicast(&ipv6_hdr(skb)->daddr)) { struct inet6_dev *idev = ip6_dst_idev(skb_dst(skb));