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Subject[PATCH 4.16 11/81] ipv6: sr: fix NULL pointer dereference in seg6_do_srh_encap()- v4 pkts
Date
4.16-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Ahmed Abdelsalam <amsalam20@gmail.com>


[ Upstream commit a957fa190aa9d9168b33d460a5241a6d088c6265 ]

In case of seg6 in encap mode, seg6_do_srh_encap() calls set_tun_src()
in order to set the src addr of outer IPv6 header.

The net_device is required for set_tun_src(). However calling ip6_dst_idev()
on dst_entry in case of IPv4 traffic results on the following bug.

Using just dst->dev should fix this BUG.

[ 196.242461] BUG: unable to handle kernel NULL pointer dereference at 0000000000000000
[ 196.242975] PGD 800000010f076067 P4D 800000010f076067 PUD 10f060067 PMD 0
[ 196.243329] Oops: 0000 [#1] SMP PTI
[ 196.243468] Modules linked in: nfsd auth_rpcgss nfs_acl nfs lockd grace fscache sunrpc crct10dif_pclmul crc32_pclmul ghash_clmulni_intel pcbc aesni_intel aes_x86_64 crypto_simd cryptd input_leds glue_helper led_class pcspkr serio_raw mac_hid video autofs4 hid_generic usbhid hid e1000 i2c_piix4 ahci pata_acpi libahci
[ 196.244362] CPU: 2 PID: 1089 Comm: ping Not tainted 4.16.0+ #1
[ 196.244606] Hardware name: innotek GmbH VirtualBox/VirtualBox, BIOS VirtualBox 12/01/2006
[ 196.244968] RIP: 0010:seg6_do_srh_encap+0x1ac/0x300
[ 196.245236] RSP: 0018:ffffb2ce00b23a60 EFLAGS: 00010202
[ 196.245464] RAX: 0000000000000000 RBX: ffff8c7f53eea300 RCX: 0000000000000000
[ 196.245742] RDX: 0000f10000000000 RSI: ffff8c7f52085a6c RDI: ffff8c7f41166850
[ 196.246018] RBP: ffffb2ce00b23aa8 R08: 00000000000261e0 R09: ffff8c7f41166800
[ 196.246294] R10: ffffdce5040ac780 R11: ffff8c7f41166828 R12: ffff8c7f41166808
[ 196.246570] R13: ffff8c7f52085a44 R14: ffffffffb73211c0 R15: ffff8c7e69e44200
[ 196.246846] FS: 00007fc448789700(0000) GS:ffff8c7f59d00000(0000) knlGS:0000000000000000
[ 196.247286] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 196.247526] CR2: 0000000000000000 CR3: 000000010f05a000 CR4: 00000000000406e0
[ 196.247804] Call Trace:
[ 196.247972] seg6_do_srh+0x15b/0x1c0
[ 196.248156] seg6_output+0x3c/0x220
[ 196.248341] ? prandom_u32+0x14/0x20
[ 196.248526] ? ip_idents_reserve+0x6c/0x80
[ 196.248723] ? __ip_select_ident+0x90/0x100
[ 196.248923] ? ip_append_data.part.50+0x6c/0xd0
[ 196.249133] lwtunnel_output+0x44/0x70
[ 196.249328] ip_send_skb+0x15/0x40
[ 196.249515] raw_sendmsg+0x8c3/0xac0
[ 196.249701] ? _copy_from_user+0x2e/0x60
[ 196.249897] ? rw_copy_check_uvector+0x53/0x110
[ 196.250106] ? _copy_from_user+0x2e/0x60
[ 196.250299] ? copy_msghdr_from_user+0xce/0x140
[ 196.250508] sock_sendmsg+0x36/0x40
[ 196.250690] ___sys_sendmsg+0x292/0x2a0
[ 196.250881] ? _cond_resched+0x15/0x30
[ 196.251074] ? copy_termios+0x1e/0x70
[ 196.251261] ? _copy_to_user+0x22/0x30
[ 196.251575] ? tty_mode_ioctl+0x1c3/0x4e0
[ 196.251782] ? _cond_resched+0x15/0x30
[ 196.251972] ? mutex_lock+0xe/0x30
[ 196.252152] ? vvar_fault+0xd2/0x110
[ 196.252337] ? __do_fault+0x1f/0xc0
[ 196.252521] ? __handle_mm_fault+0xc1f/0x12d0
[ 196.252727] ? __sys_sendmsg+0x63/0xa0
[ 196.252919] __sys_sendmsg+0x63/0xa0
[ 196.253107] do_syscall_64+0x72/0x200
[ 196.253305] entry_SYSCALL_64_after_hwframe+0x3d/0xa2
[ 196.253530] RIP: 0033:0x7fc4480b0690
[ 196.253715] RSP: 002b:00007ffde9f252f8 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
[ 196.254053] RAX: ffffffffffffffda RBX: 0000000000000040 RCX: 00007fc4480b0690
[ 196.254331] RDX: 0000000000000000 RSI: 000000000060a360 RDI: 0000000000000003
[ 196.254608] RBP: 00007ffde9f253f0 R08: 00000000002d1e81 R09: 0000000000000002
[ 196.254884] R10: 00007ffde9f250c0 R11: 0000000000000246 R12: 0000000000b22070
[ 196.255205] R13: 20c49ba5e353f7cf R14: 431bde82d7b634db R15: 00007ffde9f278fe
[ 196.255484] Code: a5 0f b6 45 c0 41 88 41 28 41 0f b6 41 2c 48 c1 e0 04 49 8b 54 01 38 49 8b 44 01 30 49 89 51 20 49 89 41 18 48 8b 83 b0 00 00 00 <48> 8b 30 49 8b 86 08 0b 00 00 48 8b 40 20 48 8b 50 08 48 0b 10
[ 196.256190] RIP: seg6_do_srh_encap+0x1ac/0x300 RSP: ffffb2ce00b23a60
[ 196.256445] CR2: 0000000000000000
[ 196.256676] ---[ end trace 71af7d093603885c ]---

Fixes: 8936ef7604c11 ("ipv6: sr: fix NULL pointer dereference when setting encap source address")
Signed-off-by: Ahmed Abdelsalam <amsalam20@gmail.com>
Acked-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 | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/net/ipv6/seg6_iptunnel.c
+++ b/net/ipv6/seg6_iptunnel.c
@@ -136,7 +136,7 @@ int seg6_do_srh_encap(struct sk_buff *sk
isrh->nexthdr = proto;

hdr->daddr = isrh->segments[isrh->first_segment];
- set_tun_src(net, ip6_dst_idev(dst)->dev, &hdr->daddr, &hdr->saddr);
+ set_tun_src(net, dst->dev, &hdr->daddr, &hdr->saddr);

#ifdef CONFIG_IPV6_SEG6_HMAC
if (sr_has_hmac(isrh)) {

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