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Guillaume Nault 56366fa0ad l2tp: fix racy SOCK_ZAPPED flag check in l2tp_ip{,6}_bind() 
[ Upstream commit 32c231164b ]

Lock socket before checking the SOCK_ZAPPED flag in l2tp_ip6_bind().
Without lock, a concurrent call could modify the socket flags between
the sock_flag(sk, SOCK_ZAPPED) test and the lock_sock() call. This way,
a socket could be inserted twice in l2tp_ip6_bind_table. Releasing it
would then leave a stale pointer there, generating use-after-free
errors when walking through the list or modifying adjacent entries.

BUG: KASAN: use-after-free in l2tp_ip6_close+0x22e/0x290 at addr ffff8800081b0ed8
Write of size 8 by task syz-executor/10987
CPU: 0 PID: 10987 Comm: syz-executor Not tainted 4.8.0+ #39
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.8.2-0-g33fbe13 by qemu-project.org 04/01/2014
 ffff880031d97838 ffffffff829f835b ffff88001b5a1640 ffff8800081b0ec0
 ffff8800081b15a0 ffff8800081b6d20 ffff880031d97860 ffffffff8174d3cc
 ffff880031d978f0 ffff8800081b0e80 ffff88001b5a1640 ffff880031d978e0
Call Trace:
 [<ffffffff829f835b>] dump_stack+0xb3/0x118 lib/dump_stack.c:15
 [<ffffffff8174d3cc>] kasan_object_err+0x1c/0x70 mm/kasan/report.c:156
 [<     inline     >] print_address_description mm/kasan/report.c:194
 [<ffffffff8174d666>] kasan_report_error+0x1f6/0x4d0 mm/kasan/report.c:283
 [<     inline     >] kasan_report mm/kasan/report.c:303
 [<ffffffff8174db7e>] __asan_report_store8_noabort+0x3e/0x40 mm/kasan/report.c:329
 [<     inline     >] __write_once_size ./include/linux/compiler.h:249
 [<     inline     >] __hlist_del ./include/linux/list.h:622
 [<     inline     >] hlist_del_init ./include/linux/list.h:637
 [<ffffffff8579047e>] l2tp_ip6_close+0x22e/0x290 net/l2tp/l2tp_ip6.c:239
 [<ffffffff850b2dfd>] inet_release+0xed/0x1c0 net/ipv4/af_inet.c:415
 [<ffffffff851dc5a0>] inet6_release+0x50/0x70 net/ipv6/af_inet6.c:422
 [<ffffffff84c4581d>] sock_release+0x8d/0x1d0 net/socket.c:570
 [<ffffffff84c45976>] sock_close+0x16/0x20 net/socket.c:1017
 [<ffffffff817a108c>] __fput+0x28c/0x780 fs/file_table.c:208
 [<ffffffff817a1605>] ____fput+0x15/0x20 fs/file_table.c:244
 [<ffffffff813774f9>] task_work_run+0xf9/0x170
 [<ffffffff81324aae>] do_exit+0x85e/0x2a00
 [<ffffffff81326dc8>] do_group_exit+0x108/0x330
 [<ffffffff81348cf7>] get_signal+0x617/0x17a0 kernel/signal.c:2307
 [<ffffffff811b49af>] do_signal+0x7f/0x18f0
 [<ffffffff810039bf>] exit_to_usermode_loop+0xbf/0x150 arch/x86/entry/common.c:156
 [<     inline     >] prepare_exit_to_usermode arch/x86/entry/common.c:190
 [<ffffffff81006060>] syscall_return_slowpath+0x1a0/0x1e0 arch/x86/entry/common.c:259
 [<ffffffff85e4d726>] entry_SYSCALL_64_fastpath+0xc4/0xc6
Object at ffff8800081b0ec0, in cache L2TP/IPv6 size: 1448
Allocated:
PID = 10987
 [ 1116.897025] [<ffffffff811ddcb6>] save_stack_trace+0x16/0x20
 [ 1116.897025] [<ffffffff8174c736>] save_stack+0x46/0xd0
 [ 1116.897025] [<ffffffff8174c9ad>] kasan_kmalloc+0xad/0xe0
 [ 1116.897025] [<ffffffff8174cee2>] kasan_slab_alloc+0x12/0x20
 [ 1116.897025] [<     inline     >] slab_post_alloc_hook mm/slab.h:417
 [ 1116.897025] [<     inline     >] slab_alloc_node mm/slub.c:2708
 [ 1116.897025] [<     inline     >] slab_alloc mm/slub.c:2716
 [ 1116.897025] [<ffffffff817476a8>] kmem_cache_alloc+0xc8/0x2b0 mm/slub.c:2721
 [ 1116.897025] [<ffffffff84c4f6a9>] sk_prot_alloc+0x69/0x2b0 net/core/sock.c:1326
 [ 1116.897025] [<ffffffff84c58ac8>] sk_alloc+0x38/0xae0 net/core/sock.c:1388
 [ 1116.897025] [<ffffffff851ddf67>] inet6_create+0x2d7/0x1000 net/ipv6/af_inet6.c:182
 [ 1116.897025] [<ffffffff84c4af7b>] __sock_create+0x37b/0x640 net/socket.c:1153
 [ 1116.897025] [<     inline     >] sock_create net/socket.c:1193
 [ 1116.897025] [<     inline     >] SYSC_socket net/socket.c:1223
 [ 1116.897025] [<ffffffff84c4b46f>] SyS_socket+0xef/0x1b0 net/socket.c:1203
 [ 1116.897025] [<ffffffff85e4d685>] entry_SYSCALL_64_fastpath+0x23/0xc6
Freed:
PID = 10987
 [ 1116.897025] [<ffffffff811ddcb6>] save_stack_trace+0x16/0x20
 [ 1116.897025] [<ffffffff8174c736>] save_stack+0x46/0xd0
 [ 1116.897025] [<ffffffff8174cf61>] kasan_slab_free+0x71/0xb0
 [ 1116.897025] [<     inline     >] slab_free_hook mm/slub.c:1352
 [ 1116.897025] [<     inline     >] slab_free_freelist_hook mm/slub.c:1374
 [ 1116.897025] [<     inline     >] slab_free mm/slub.c:2951
 [ 1116.897025] [<ffffffff81748b28>] kmem_cache_free+0xc8/0x330 mm/slub.c:2973
 [ 1116.897025] [<     inline     >] sk_prot_free net/core/sock.c:1369
 [ 1116.897025] [<ffffffff84c541eb>] __sk_destruct+0x32b/0x4f0 net/core/sock.c:1444
 [ 1116.897025] [<ffffffff84c5aca4>] sk_destruct+0x44/0x80 net/core/sock.c:1452
 [ 1116.897025] [<ffffffff84c5ad33>] __sk_free+0x53/0x220 net/core/sock.c:1460
 [ 1116.897025] [<ffffffff84c5af23>] sk_free+0x23/0x30 net/core/sock.c:1471
 [ 1116.897025] [<ffffffff84c5cb6c>] sk_common_release+0x28c/0x3e0 ./include/net/sock.h:1589
 [ 1116.897025] [<ffffffff8579044e>] l2tp_ip6_close+0x1fe/0x290 net/l2tp/l2tp_ip6.c:243
 [ 1116.897025] [<ffffffff850b2dfd>] inet_release+0xed/0x1c0 net/ipv4/af_inet.c:415
 [ 1116.897025] [<ffffffff851dc5a0>] inet6_release+0x50/0x70 net/ipv6/af_inet6.c:422
 [ 1116.897025] [<ffffffff84c4581d>] sock_release+0x8d/0x1d0 net/socket.c:570
 [ 1116.897025] [<ffffffff84c45976>] sock_close+0x16/0x20 net/socket.c:1017
 [ 1116.897025] [<ffffffff817a108c>] __fput+0x28c/0x780 fs/file_table.c:208
 [ 1116.897025] [<ffffffff817a1605>] ____fput+0x15/0x20 fs/file_table.c:244
 [ 1116.897025] [<ffffffff813774f9>] task_work_run+0xf9/0x170
 [ 1116.897025] [<ffffffff81324aae>] do_exit+0x85e/0x2a00
 [ 1116.897025] [<ffffffff81326dc8>] do_group_exit+0x108/0x330
 [ 1116.897025] [<ffffffff81348cf7>] get_signal+0x617/0x17a0 kernel/signal.c:2307
 [ 1116.897025] [<ffffffff811b49af>] do_signal+0x7f/0x18f0
 [ 1116.897025] [<ffffffff810039bf>] exit_to_usermode_loop+0xbf/0x150 arch/x86/entry/common.c:156
 [ 1116.897025] [<     inline     >] prepare_exit_to_usermode arch/x86/entry/common.c:190
 [ 1116.897025] [<ffffffff81006060>] syscall_return_slowpath+0x1a0/0x1e0 arch/x86/entry/common.c:259
 [ 1116.897025] [<ffffffff85e4d726>] entry_SYSCALL_64_fastpath+0xc4/0xc6
Memory state around the buggy address:
 ffff8800081b0d80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8800081b0e00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff8800081b0e80: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
                                                    ^
 ffff8800081b0f00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8800081b0f80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb

==================================================================

The same issue exists with l2tp_ip_bind() and l2tp_ip_bind_table.

Fixes: c51ce49735 ("l2tp: fix oops in L2TP IP sockets for connect() AF_UNSPEC case")
Reported-by: Baozeng Ding <sploving1@gmail.com>
Reported-by: Andrey Konovalov <andreyknvl@google.com>
Tested-by: Baozeng Ding <sploving1@gmail.com>
Signed-off-by: Guillaume Nault <g.nault@alphalink.fr>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2016-12-10 19:07:23 +01:00
..
6lowpan 6lowpan: put mcast compression in an own function 2015-10-21 00:49:25 +02:00
9p IB/cma: Add support for network namespaces 2015-10-28 12:32:48 -04:00
802
8021q net: add recursion limit to GRO 2016-11-15 07:46:38 +01:00
appletalk
atm atm: deal with setting entry before mkip was called 2015-09-17 22:13:32 -07:00
ax25 AX.25: Close socket connection on session completion 2016-07-11 09:31:12 -07:00
batman-adv batman-adv: remove unused callback from batadv_algo_ops struct 2016-10-07 15:23:47 +02:00
bluetooth Bluetooth: Fix l2cap_sock_setsockopt() with optname BT_RCVMTU 2016-08-20 18:09:19 +02:00
bridge bridge: multicast: restore perm router ports on multicast enable 2016-11-15 07:46:38 +01:00
caif net: caif: fix misleading indentation 2016-09-30 10:18:35 +02:00
can can: bcm: fix warning in bcm_connect/proc_register 2016-11-26 09:54:52 +01:00
ceph libceph: apply new_state before new_up_client on incrementals 2016-08-10 11:49:29 +02:00
core rtnetlink: fix FDB size computation 2016-12-10 19:07:22 +01:00
dcb net/dcb: make dcbnl.c explicitly non-modular 2015-10-09 07:52:27 -07:00
dccp ipv6: dccp: add missing bind_conflict to dccp_ipv6_mapped 2016-11-21 10:06:40 +01:00
decnet decnet: Do not build routes to devices without decnet private data. 2016-05-18 17:06:35 -07:00
dns_resolver net: dns_resolver: convert time_t to time64_t 2015-11-18 16:27:46 -05:00
dsa net: dsa: use switchdev obj for VLAN add/del ops 2015-11-01 15:56:11 -05:00
ethernet net: add recursion limit to GRO 2016-11-15 07:46:38 +01:00
hsr net/hsr: fix a warning message 2015-11-23 14:56:15 -05:00
ieee802154 net: fix percpu memory leaks 2015-11-02 22:47:14 -05:00
ipv4 tcp: take care of truncations done by sk_filter() 2016-11-21 10:06:40 +01:00
ipv6 ip6_tunnel: disable caching when the traffic class is inherited 2016-12-10 19:07:22 +01:00
ipx
irda net/irda: handle iriap_register_lsap() allocation failure 2016-09-30 10:18:36 +02:00
iucv af_iucv: Validate socket address length in iucv_sock_bind() 2016-03-03 15:07:03 -08:00
key af_key: fix two typos 2015-10-23 03:05:19 -07:00
l2tp l2tp: fix racy SOCK_ZAPPED flag check in l2tp_ip{,6}_bind() 2016-12-10 19:07:23 +01:00
l3mdev net: Add netif_is_l3_slave 2015-10-07 04:27:43 -07:00
lapb
llc net: fix infoleak in llc 2016-05-18 17:06:40 -07:00
mac80211 mac80211: discard multicast and 4-addr A-MSDUs 2016-11-10 16:36:35 +01:00
mac802154 mac802154: llsec: use kzfree 2015-10-21 00:49:24 +02:00
mpls mpls: find_outdev: check for err ptr in addition to NULL check 2016-04-20 15:42:07 +09:00
netfilter netfilter: nft_dynset: fix element timeout for HZ != 1000 2016-11-26 09:54:54 +01:00
netlabel netlabel: add address family checks to netlbl_{sock,req}_delattr() 2016-08-20 18:09:22 +02:00
netlink netlink: do not enter direct reclaim from netlink_dump() 2016-11-15 07:46:37 +01:00
netrom
nfc net: rename SOCK_ASYNC_NOSPACE and SOCK_ASYNC_WAITDATA 2015-12-01 15:45:05 -05:00
openvswitch vxlan, gre, geneve: Set a large MTU on ovs-created tunnel devices 2016-06-24 10:18:18 -07:00
packet packet: on direct_xmit, limit tso and csum to supported devices 2016-11-15 07:46:39 +01:00
phonet phonet: properly unshare skbs in phonet_rcv() 2016-01-31 11:29:00 -08:00
rds rds: fix an infoleak in rds_inc_info_copy 2016-09-15 08:27:51 +02:00
rfkill rfkill: fix rfkill_fop_read wait_event usage 2016-03-03 15:07:26 -08:00
rose
rxrpc net: rename SOCK_ASYNC_NOSPACE and SOCK_ASYNC_WAITDATA 2015-12-01 15:45:05 -05:00
sched net sched filters: fix notification of filter delete with proper handle 2016-11-15 07:46:39 +01:00
sctp sctp: assign assoc_id earlier in __sctp_connect 2016-11-21 10:06:40 +01:00
sunrpc sunrpc: fix write space race causing stalls 2016-10-28 03:01:31 -04:00
switchdev switchdev: pass pointer to fib_info instead of copy 2016-06-24 10:18:16 -07:00
tipc tipc: fix NULL pointer dereference in shutdown() 2016-09-30 10:18:36 +02:00
unix af_unix: conditionally use freezable blocking calls in read 2016-12-10 19:07:22 +01:00
vmw_vsock VSOCK: do not disconnect socket when peer has shutdown SEND only 2016-05-18 17:06:41 -07:00
wimax
wireless cfg80211: limit scan results cache size 2016-12-02 09:09:01 +01:00
x25 net: fix a kernel infoleak in x25 module 2016-05-18 17:06:43 -07:00
xfrm xfrm: Fix crash observed during device unregistration and decryption 2016-04-20 15:42:05 +09:00
compat.c
Kconfig net: Introduce L3 Master device abstraction 2015-09-29 20:40:32 -07:00
Makefile net: Introduce L3 Master device abstraction 2015-09-29 20:40:32 -07:00
socket.c sock: fix sendmmsg for partial sendmsg 2016-11-21 10:06:40 +01:00
sysctl_net.c net: Use ns_capable_noaudit() when determining net sysctl permissions 2016-09-15 08:27:50 +02:00