This is a note to let you know that I've just added the patch titled vti: fix use after free in vti_tunnel_xmit/vti6_tnl_xmit to the 3.18-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: vti-fix-use-after-free-in-vti_tunnel_xmit-vti6_tnl_xmit.patch and it can be found in the queue-3.18 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From foo@baz Thu Oct 19 14:44:13 CEST 2017 From: Alexey Kodanev <alexey.kodanev@xxxxxxxxxx> Date: Tue, 26 Sep 2017 15:14:29 +0300 Subject: vti: fix use after free in vti_tunnel_xmit/vti6_tnl_xmit From: Alexey Kodanev <alexey.kodanev@xxxxxxxxxx> [ Upstream commit 36f6ee22d2d66046e369757ec6bbe1c482957ba6 ] When running LTP IPsec tests, KASan might report: BUG: KASAN: use-after-free in vti_tunnel_xmit+0xeee/0xff0 [ip_vti] Read of size 4 at addr ffff880dc6ad1980 by task swapper/0/0 ... Call Trace: <IRQ> dump_stack+0x63/0x89 print_address_description+0x7c/0x290 kasan_report+0x28d/0x370 ? vti_tunnel_xmit+0xeee/0xff0 [ip_vti] __asan_report_load4_noabort+0x19/0x20 vti_tunnel_xmit+0xeee/0xff0 [ip_vti] ? vti_init_net+0x190/0x190 [ip_vti] ? save_stack_trace+0x1b/0x20 ? save_stack+0x46/0xd0 dev_hard_start_xmit+0x147/0x510 ? icmp_echo.part.24+0x1f0/0x210 __dev_queue_xmit+0x1394/0x1c60 ... Freed by task 0: save_stack_trace+0x1b/0x20 save_stack+0x46/0xd0 kasan_slab_free+0x70/0xc0 kmem_cache_free+0x81/0x1e0 kfree_skbmem+0xb1/0xe0 kfree_skb+0x75/0x170 kfree_skb_list+0x3e/0x60 __dev_queue_xmit+0x1298/0x1c60 dev_queue_xmit+0x10/0x20 neigh_resolve_output+0x3a8/0x740 ip_finish_output2+0x5c0/0xe70 ip_finish_output+0x4ba/0x680 ip_output+0x1c1/0x3a0 xfrm_output_resume+0xc65/0x13d0 xfrm_output+0x1e4/0x380 xfrm4_output_finish+0x5c/0x70 Can be fixed if we get skb->len before dst_output(). Fixes: b9959fd3b0fa ("vti: switch to new ip tunnel code") Fixes: 22e1b23dafa8 ("vti6: Support inter address family tunneling.") Signed-off-by: Alexey Kodanev <alexey.kodanev@xxxxxxxxxx> Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- net/ipv4/ip_vti.c | 3 ++- net/ipv6/ip6_vti.c | 3 ++- 2 files changed, 4 insertions(+), 2 deletions(-) --- a/net/ipv4/ip_vti.c +++ b/net/ipv4/ip_vti.c @@ -156,6 +156,7 @@ static netdev_tx_t vti_xmit(struct sk_bu struct ip_tunnel_parm *parms = &tunnel->parms; struct dst_entry *dst = skb_dst(skb); struct net_device *tdev; /* Device to other host */ + int pkt_len = skb->len; int err; if (!dst) { @@ -199,7 +200,7 @@ static netdev_tx_t vti_xmit(struct sk_bu err = dst_output(skb); if (net_xmit_eval(err) == 0) - err = skb->len; + err = pkt_len; iptunnel_xmit_stats(err, &dev->stats, dev->tstats); return NETDEV_TX_OK; --- a/net/ipv6/ip6_vti.c +++ b/net/ipv6/ip6_vti.c @@ -416,6 +416,7 @@ vti6_xmit(struct sk_buff *skb, struct ne struct net_device_stats *stats = &t->dev->stats; struct dst_entry *dst = skb_dst(skb); struct net_device *tdev; + int pkt_len = skb->len; int err = -1; if (!dst) @@ -450,7 +451,7 @@ vti6_xmit(struct sk_buff *skb, struct ne struct pcpu_sw_netstats *tstats = this_cpu_ptr(dev->tstats); u64_stats_update_begin(&tstats->syncp); - tstats->tx_bytes += skb->len; + tstats->tx_bytes += pkt_len; tstats->tx_packets++; u64_stats_update_end(&tstats->syncp); } else { Patches currently in stable-queue which might be from alexey.kodanev@xxxxxxxxxx are queue-3.18/vti-fix-use-after-free-in-vti_tunnel_xmit-vti6_tnl_xmit.patch