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alistair23-linux/net/ipv6
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Eric Dumazet db3fa27102 ipv6/addrconf: fix potential NULL deref in inet6_set_link_af() 
__in6_dev_get(dev) called from inet6_set_link_af() can return NULL.

The needed check has been recently removed, let's add it back.

While do_setlink() does call validate_linkmsg() :
...
err = validate_linkmsg(dev, tb); /* OK at this point */
...

It is possible that the following call happening before the
->set_link_af() removes IPv6 if MTU is less than 1280 :

if (tb[IFLA_MTU]) {
    err = dev_set_mtu_ext(dev, nla_get_u32(tb[IFLA_MTU]), extack);
    if (err < 0)
          goto errout;
    status |= DO_SETLINK_MODIFIED;
}
...

if (tb[IFLA_AF_SPEC]) {
   ...
   err = af_ops->set_link_af(dev, af);
      ->inet6_set_link_af() // CRASH because idev is NULL

Please note that IPv4 is immune to the bug since inet_set_link_af() does :

struct in_device *in_dev = __in_dev_get_rcu(dev);
if (!in_dev)
    return -EAFNOSUPPORT;

This problem has been mentioned in commit cf7afbfeb8 ("rtnl: make
link af-specific updates atomic") changelog :

    This method is not fail proof, while it is currently sufficient
    to make set_link_af() inerrable and thus 100% atomic, the
    validation function method will not be able to detect all error
    scenarios in the future, there will likely always be errors
    depending on states which are f.e. not protected by rtnl_mutex
    and thus may change between validation and setting.

IPv6: ADDRCONF(NETDEV_CHANGE): lo: link becomes ready
general protection fault, probably for non-canonical address 0xdffffc0000000056: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x00000000000002b0-0x00000000000002b7]
CPU: 0 PID: 9698 Comm: syz-executor712 Not tainted 5.5.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:inet6_set_link_af+0x66e/0xae0 net/ipv6/addrconf.c:5733
Code: 38 d0 7f 08 84 c0 0f 85 20 03 00 00 48 8d bb b0 02 00 00 45 0f b6 64 24 04 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <0f> b6 04 02 84 c0 74 08 3c 03 0f 8e 1a 03 00 00 44 89 a3 b0 02 00
RSP: 0018:ffffc90005b06d40 EFLAGS: 00010206
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: ffffffff86df39a6
RDX: 0000000000000056 RSI: ffffffff86df3e74 RDI: 00000000000002b0
RBP: ffffc90005b06e70 R08: ffff8880a2ac0380 R09: ffffc90005b06db0
R10: fffff52000b60dbe R11: ffffc90005b06df7 R12: 0000000000000000
R13: 0000000000000000 R14: ffff8880a1fcc424 R15: dffffc0000000000
FS:  0000000000c46880(0000) GS:ffff8880ae800000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055f0494ca0d0 CR3: 000000009e4ac000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 do_setlink+0x2a9f/0x3720 net/core/rtnetlink.c:2754
 rtnl_group_changelink net/core/rtnetlink.c:3103 [inline]
 __rtnl_newlink+0xdd1/0x1790 net/core/rtnetlink.c:3257
 rtnl_newlink+0x69/0xa0 net/core/rtnetlink.c:3377
 rtnetlink_rcv_msg+0x45e/0xaf0 net/core/rtnetlink.c:5438
 netlink_rcv_skb+0x177/0x450 net/netlink/af_netlink.c:2477
 rtnetlink_rcv+0x1d/0x30 net/core/rtnetlink.c:5456
 netlink_unicast_kernel net/netlink/af_netlink.c:1302 [inline]
 netlink_unicast+0x59e/0x7e0 net/netlink/af_netlink.c:1328
 netlink_sendmsg+0x91c/0xea0 net/netlink/af_netlink.c:1917
 sock_sendmsg_nosec net/socket.c:652 [inline]
 sock_sendmsg+0xd7/0x130 net/socket.c:672
 ____sys_sendmsg+0x753/0x880 net/socket.c:2343
 ___sys_sendmsg+0x100/0x170 net/socket.c:2397
 __sys_sendmsg+0x105/0x1d0 net/socket.c:2430
 __do_sys_sendmsg net/socket.c:2439 [inline]
 __se_sys_sendmsg net/socket.c:2437 [inline]
 __x64_sys_sendmsg+0x78/0xb0 net/socket.c:2437
 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x4402e9
Code: 18 89 d0 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 fb 13 fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fffd62fbcf8 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 00000000004402e9
RDX: 0000000000000000 RSI: 0000000020000080 RDI: 0000000000000003
RBP: 00000000006ca018 R08: 0000000000000008 R09: 00000000004002c8
R10: 0000000000000005 R11: 0000000000000246 R12: 0000000000401b70
R13: 0000000000401c00 R14: 0000000000000000 R15: 0000000000000000
Modules linked in:
---[ end trace cfa7664b8fdcdff3 ]---
RIP: 0010:inet6_set_link_af+0x66e/0xae0 net/ipv6/addrconf.c:5733
Code: 38 d0 7f 08 84 c0 0f 85 20 03 00 00 48 8d bb b0 02 00 00 45 0f b6 64 24 04 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <0f> b6 04 02 84 c0 74 08 3c 03 0f 8e 1a 03 00 00 44 89 a3 b0 02 00
RSP: 0018:ffffc90005b06d40 EFLAGS: 00010206
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: ffffffff86df39a6
RDX: 0000000000000056 RSI: ffffffff86df3e74 RDI: 00000000000002b0
RBP: ffffc90005b06e70 R08: ffff8880a2ac0380 R09: ffffc90005b06db0
R10: fffff52000b60dbe R11: ffffc90005b06df7 R12: 0000000000000000
R13: 0000000000000000 R14: ffff8880a1fcc424 R15: dffffc0000000000
FS:  0000000000c46880(0000) GS:ffff8880ae900000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020000004 CR3: 000000009e4ac000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400

Fixes: 7dc2bccab0 ("Validate required parameters in inet6_validate_link_af")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Bisected-and-reported-by: syzbot <syzkaller@googlegroups.com>
Cc: Maxim Mikityanskiy <maximmi@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2020-02-07 18:43:23 +01:00
..
ila
netfilter net: Fix Kconfig indentation, continued 2019-11-21 12:00:21 -08:00
addrconf.c ipv6/addrconf: fix potential NULL deref in inet6_set_link_af() 2020-02-07 18:43:23 +01:00
addrconf_core.c net: ipv6_stub: use ip6_dst_lookup_flow instead of ip6_dst_lookup 2019-12-04 12:27:13 -08:00
addrlabel.c
af_inet6.c net: ipv6_stub: use ip6_dst_lookup_flow instead of ip6_dst_lookup 2019-12-04 12:27:13 -08:00
ah6.c
anycast.c
calipso.c
datagram.c net: ipv6: add net argument to ip6_dst_lookup_flow 2019-12-04 12:27:12 -08:00
esp6.c
esp6_offload.c xfrm: support output_mark for offload ESP packets 2020-01-15 12:18:35 +01:00
exthdrs.c
exthdrs_core.c
exthdrs_offload.c
fib6_notifier.c net: fib_notifier: propagate extack down to the notifier block callback 2019-10-04 11:10:56 -07:00
fib6_rules.c net: fib_notifier: propagate extack down to the notifier block callback 2019-10-04 11:10:56 -07:00
fou6.c
icmp.c net: icmp6: provide input address for traceroute6 2019-11-03 17:26:53 -08:00
inet6_connection_sock.c net: add bool confirm_neigh parameter for dst_ops.update_pmtu 2019-12-24 22:28:54 -08:00
inet6_hashtables.c net: annotate accesses to sk->sk_incoming_cpu 2019-10-30 13:24:25 -07:00
ip6_checksum.c
ip6_fib.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2020-01-26 10:40:21 +01:00
ip6_flowlabel.c
ip6_gre.c net: ip6_gre: fix moving ip6gre between namespaces 2020-01-20 09:59:24 +01:00
ip6_icmp.c
ip6_input.c ipv6: introduce and uses route look hints for list input. 2019-11-21 14:45:55 -08:00
ip6_offload.c
ip6_offload.h
ip6_output.c net: ipv6: add net argument to ip6_dst_lookup_flow 2019-12-04 12:27:12 -08:00
ip6_tunnel.c net, ip6_tunnel: fix namespaces move 2020-01-22 21:13:40 +01:00
ip6_udp_tunnel.c
ip6_vti.c vti[6]: fix packet tx through bpf_redirect() 2020-01-14 08:55:38 +01:00
ip6mr.c net: fib_notifier: propagate extack down to the notifier block callback 2019-10-04 11:10:56 -07:00
ipcomp6.c
ipv6_sockglue.c net-ipv6: IPV6_TRANSPARENT - check NET_RAW prior to NET_ADMIN 2019-11-21 19:15:20 -08:00
Kconfig
Makefile
mcast.c mld: fix memory leak in mld_del_delrec() 2019-08-28 14:47:35 -07:00
mcast_snoop.c
mip6.c
ndisc.c
netfilter.c net: ensure correct skb->tstamp in various fragmenters 2019-10-18 10:02:37 -07:00
output_core.c
ping.c ipv6: Fix the link time qualifier of 'ping_v6_proc_exit_net()' 2019-09-12 11:20:33 +01:00
proc.c
protocol.c
raw.c net: ipv6: add net argument to ip6_dst_lookup_flow 2019-12-04 12:27:12 -08:00
reassembly.c
route.c ipv6: Add "offload" and "trap" indications to routes 2020-01-14 18:53:35 -08:00
seg6.c
seg6_hmac.c
seg6_iptunnel.c
seg6_local.c ipv6: sr: remove SKB_GSO_IPXIP6 on End.D* actions 2020-01-21 10:17:07 +01:00
sit.c sit: do not confirm neighbor when do pmtu update 2019-12-24 22:28:55 -08:00
syncookies.c mptcp: handle tcp fallback when using syn cookies 2020-01-29 17:45:20 +01:00
sysctl_net_ipv6.c
tcp_ipv6.c mptcp: Fix undefined mptcp_handle_ipv6_mapped for modular IPV6 2020-01-30 10:55:54 +01:00
tcpv6_offload.c
tunnel6.c
udp.c net: udp: use skb_list_walk_safe helper for gso segments 2020-01-14 11:48:41 -08:00
udp_impl.h
udp_offload.c udp: Support UDP fraglist GRO/GSO. 2020-01-27 11:00:21 +01:00
udplite.c
xfrm6_input.c
xfrm6_output.c netfilter: Support iif matches in POSTROUTING 2019-11-15 23:44:48 +01:00
xfrm6_policy.c net: add bool confirm_neigh parameter for dst_ops.update_pmtu 2019-12-24 22:28:54 -08:00
xfrm6_protocol.c
xfrm6_state.c
xfrm6_tunnel.c