4.15-stable review patch. If anyone has any objections, please let me know.
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From: David Lebrun dlebrun@google.com
[ Upstream commit 8936ef7604c11b5d701580d779e0f5684abc7b68 ]
When using seg6 in encap mode, we call ipv6_dev_get_saddr() to set the source address of the outer IPv6 header, in case none was specified. Using skb->dev can lead to BUG() when it is in an inconsistent state. This patch uses the net_device attached to the skb's dst instead.
[940807.667429] BUG: unable to handle kernel NULL pointer dereference at 000000000000047c [940807.762427] IP: ipv6_dev_get_saddr+0x8b/0x1d0 [940807.815725] PGD 0 P4D 0 [940807.847173] Oops: 0000 [#1] SMP PTI [940807.890073] Modules linked in: [940807.927765] CPU: 6 PID: 0 Comm: swapper/6 Tainted: G W 4.16.0-rc1-seg6bpf+ #2 [940808.028988] Hardware name: HP ProLiant DL120 G6/ProLiant DL120 G6, BIOS O26 09/06/2010 [940808.128128] RIP: 0010:ipv6_dev_get_saddr+0x8b/0x1d0 [940808.187667] RSP: 0018:ffff88043fd836b0 EFLAGS: 00010206 [940808.251366] RAX: 0000000000000005 RBX: ffff88042cb1c860 RCX: 00000000000000fe [940808.338025] RDX: 00000000000002c0 RSI: ffff88042cb1c860 RDI: 0000000000004500 [940808.424683] RBP: ffff88043fd83740 R08: 0000000000000000 R09: ffffffffffffffff [940808.511342] R10: 0000000000000040 R11: 0000000000000000 R12: ffff88042cb1c850 [940808.598012] R13: ffffffff8208e380 R14: ffff88042ac8da00 R15: 0000000000000002 [940808.684675] FS: 0000000000000000(0000) GS:ffff88043fd80000(0000) knlGS:0000000000000000 [940808.783036] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [940808.852975] CR2: 000000000000047c CR3: 00000004255fe000 CR4: 00000000000006e0 [940808.939634] Call Trace: [940808.970041] <IRQ> [940808.995250] ? ip6t_do_table+0x265/0x640 [940809.043341] seg6_do_srh_encap+0x28f/0x300 [940809.093516] ? seg6_do_srh+0x1a0/0x210 [940809.139528] seg6_do_srh+0x1a0/0x210 [940809.183462] seg6_output+0x28/0x1e0 [940809.226358] lwtunnel_output+0x3f/0x70 [940809.272370] ip6_xmit+0x2b8/0x530 [940809.313185] ? ac6_proc_exit+0x20/0x20 [940809.359197] inet6_csk_xmit+0x7d/0xc0 [940809.404173] tcp_transmit_skb+0x548/0x9a0 [940809.453304] __tcp_retransmit_skb+0x1a8/0x7a0 [940809.506603] ? ip6_default_advmss+0x40/0x40 [940809.557824] ? tcp_current_mss+0x24/0x90 [940809.605925] tcp_retransmit_skb+0xd/0x80 [940809.654016] tcp_xmit_retransmit_queue.part.17+0xf9/0x210 [940809.719797] tcp_ack+0xa47/0x1110 [940809.760612] tcp_rcv_established+0x13c/0x570 [940809.812865] tcp_v6_do_rcv+0x151/0x3d0 [940809.858879] tcp_v6_rcv+0xa5c/0xb10 [940809.901770] ? seg6_output+0xdd/0x1e0 [940809.946745] ip6_input_finish+0xbb/0x460 [940809.994837] ip6_input+0x74/0x80 [940810.034612] ? ip6_rcv_finish+0xb0/0xb0 [940810.081663] ipv6_rcv+0x31c/0x4c0 ...
Fixes: 6c8702c60b886 ("ipv6: sr: add support for SRH encapsulation and injection with lwtunnels") Reported-by: Tom Herbert tom@quantonium.net Signed-off-by: David Lebrun dlebrun@google.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/ipv6/seg6_iptunnel.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)
--- a/net/ipv6/seg6_iptunnel.c +++ b/net/ipv6/seg6_iptunnel.c @@ -93,7 +93,8 @@ static void set_tun_src(struct net *net, /* encapsulate an IPv6 packet within an outer IPv6 header with a given SRH */ int seg6_do_srh_encap(struct sk_buff *skb, struct ipv6_sr_hdr *osrh, int proto) { - struct net *net = dev_net(skb_dst(skb)->dev); + struct dst_entry *dst = skb_dst(skb); + struct net *net = dev_net(dst->dev); struct ipv6hdr *hdr, *inner_hdr; struct ipv6_sr_hdr *isrh; int hdrlen, tot_len, err; @@ -134,7 +135,7 @@ int seg6_do_srh_encap(struct sk_buff *sk isrh->nexthdr = proto;
hdr->daddr = isrh->segments[isrh->first_segment]; - set_tun_src(net, skb->dev, &hdr->daddr, &hdr->saddr); + set_tun_src(net, ip6_dst_idev(dst)->dev, &hdr->daddr, &hdr->saddr);
#ifdef CONFIG_IPV6_SEG6_HMAC if (sr_has_hmac(isrh)) {