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| author | David Lebrun <dlebrun@google.com> | 2018-03-20 17:44:56 +0300 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2018-03-22 19:22:45 +0300 |
| commit | 8936ef7604c11b5d701580d779e0f5684abc7b68 (patch) | |
| tree | 6c611715906e326c9ae0961d8c3e6ef98650fd2f /net | |
| parent | 191f86ca8ef27f7a492fd1c03620498c6e94f0ac (diff) | |
| download | linux-8936ef7604c11b5d701580d779e0f5684abc7b68.tar.xz | |
ipv6: sr: fix NULL pointer dereference when setting encap source address
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>
Diffstat (limited to 'net')
| -rw-r--r-- | net/ipv6/seg6_iptunnel.c | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/net/ipv6/seg6_iptunnel.c b/net/ipv6/seg6_iptunnel.c index 8367b859a934..7a78dcfda68a 100644 --- a/net/ipv6/seg6_iptunnel.c +++ b/net/ipv6/seg6_iptunnel.c @@ -93,7 +93,8 @@ static void set_tun_src(struct net *net, struct net_device *dev, /* 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 *skb, struct ipv6_sr_hdr *osrh, int proto) 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)) { |