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Kuniyuki Iwashima ba9f7c16ec ipvlan: Fix use-after-free in ipvlan_get_iflink(). 
[ Upstream commit cb358ff941 ]

syzbot presented an use-after-free report [0] regarding ipvlan and
linkwatch.

ipvlan does not hold a refcnt of the lower device unlike vlan and
macvlan.

If the linkwatch work is triggered for the ipvlan dev, the lower dev
might have already been freed, resulting in UAF of ipvlan->phy_dev in
ipvlan_get_iflink().

We can delay the lower dev unregistration like vlan and macvlan by
holding the lower dev's refcnt in dev->netdev_ops->ndo_init() and
releasing it in dev->priv_destructor().

Jakub pointed out calling .ndo_XXX after unregister_netdevice() has
returned is error prone and suggested [1] addressing this UAF in the
core by taking commit 750e516033 ("net: avoid potential UAF in
default_operstate()") further.

Let's assume unregistering devices DOWN and use RCU protection in
default_operstate() not to race with the device unregistration.

[0]:
BUG: KASAN: slab-use-after-free in ipvlan_get_iflink+0x84/0x88 drivers/net/ipvlan/ipvlan_main.c:353
Read of size 4 at addr ffff0000d768c0e0 by task kworker/u8:35/6944

CPU: 0 UID: 0 PID: 6944 Comm: kworker/u8:35 Not tainted 6.13.0-rc2-g9bc5c9515b48 #12 4c3cb9e8b4565456f6a355f312ff91f4f29b3c47
Hardware name: linux,dummy-virt (DT)
Workqueue: events_unbound linkwatch_event
Call trace:
 show_stack+0x38/0x50 arch/arm64/kernel/stacktrace.c:484 (C)
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0xbc/0x108 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0x16c/0x6f0 mm/kasan/report.c:489
 kasan_report+0xc0/0x120 mm/kasan/report.c:602
 __asan_report_load4_noabort+0x20/0x30 mm/kasan/report_generic.c:380
 ipvlan_get_iflink+0x84/0x88 drivers/net/ipvlan/ipvlan_main.c:353
 dev_get_iflink+0x7c/0xd8 net/core/dev.c:674
 default_operstate net/core/link_watch.c:45 [inline]
 rfc2863_policy+0x144/0x360 net/core/link_watch.c:72
 linkwatch_do_dev+0x60/0x228 net/core/link_watch.c:175
 __linkwatch_run_queue+0x2f4/0x5b8 net/core/link_watch.c:239
 linkwatch_event+0x64/0xa8 net/core/link_watch.c:282
 process_one_work+0x700/0x1398 kernel/workqueue.c:3229
 process_scheduled_works kernel/workqueue.c:3310 [inline]
 worker_thread+0x8c4/0xe10 kernel/workqueue.c:3391
 kthread+0x2b0/0x360 kernel/kthread.c:389
 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:862

Allocated by task 9303:
 kasan_save_stack mm/kasan/common.c:47 [inline]
 kasan_save_track+0x30/0x68 mm/kasan/common.c:68
 kasan_save_alloc_info+0x44/0x58 mm/kasan/generic.c:568
 poison_kmalloc_redzone mm/kasan/common.c:377 [inline]
 __kasan_kmalloc+0x84/0xa0 mm/kasan/common.c:394
 kasan_kmalloc include/linux/kasan.h:260 [inline]
 __do_kmalloc_node mm/slub.c:4283 [inline]
 __kmalloc_node_noprof+0x2a0/0x560 mm/slub.c:4289
 __kvmalloc_node_noprof+0x9c/0x230 mm/util.c:650
 alloc_netdev_mqs+0xb4/0x1118 net/core/dev.c:11209
 rtnl_create_link+0x2b8/0xb60 net/core/rtnetlink.c:3595
 rtnl_newlink_create+0x19c/0x868 net/core/rtnetlink.c:3771
 __rtnl_newlink net/core/rtnetlink.c:3896 [inline]
 rtnl_newlink+0x122c/0x15c0 net/core/rtnetlink.c:4011
 rtnetlink_rcv_msg+0x61c/0x918 net/core/rtnetlink.c:6901
 netlink_rcv_skb+0x1dc/0x398 net/netlink/af_netlink.c:2542
 rtnetlink_rcv+0x34/0x50 net/core/rtnetlink.c:6928
 netlink_unicast_kernel net/netlink/af_netlink.c:1321 [inline]
 netlink_unicast+0x618/0x838 net/netlink/af_netlink.c:1347
 netlink_sendmsg+0x5fc/0x8b0 net/netlink/af_netlink.c:1891
 sock_sendmsg_nosec net/socket.c:711 [inline]
 __sock_sendmsg net/socket.c:726 [inline]
 __sys_sendto+0x2ec/0x438 net/socket.c:2197
 __do_sys_sendto net/socket.c:2204 [inline]
 __se_sys_sendto net/socket.c:2200 [inline]
 __arm64_sys_sendto+0xe4/0x110 net/socket.c:2200
 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
 invoke_syscall+0x90/0x278 arch/arm64/kernel/syscall.c:49
 el0_svc_common+0x13c/0x250 arch/arm64/kernel/syscall.c:132
 do_el0_svc+0x54/0x70 arch/arm64/kernel/syscall.c:151
 el0_svc+0x4c/0xa8 arch/arm64/kernel/entry-common.c:744
 el0t_64_sync_handler+0x78/0x108 arch/arm64/kernel/entry-common.c:762
 el0t_64_sync+0x198/0x1a0 arch/arm64/kernel/entry.S:600

Freed by task 10200:
 kasan_save_stack mm/kasan/common.c:47 [inline]
 kasan_save_track+0x30/0x68 mm/kasan/common.c:68
 kasan_save_free_info+0x58/0x70 mm/kasan/generic.c:582
 poison_slab_object mm/kasan/common.c:247 [inline]
 __kasan_slab_free+0x48/0x68 mm/kasan/common.c:264
 kasan_slab_free include/linux/kasan.h:233 [inline]
 slab_free_hook mm/slub.c:2338 [inline]
 slab_free mm/slub.c:4598 [inline]
 kfree+0x140/0x420 mm/slub.c:4746
 kvfree+0x4c/0x68 mm/util.c:693
 netdev_release+0x94/0xc8 net/core/net-sysfs.c:2034
 device_release+0x98/0x1c0
 kobject_cleanup lib/kobject.c:689 [inline]
 kobject_release lib/kobject.c:720 [inline]
 kref_put include/linux/kref.h:65 [inline]
 kobject_put+0x2b0/0x438 lib/kobject.c:737
 netdev_run_todo+0xdd8/0xf48 net/core/dev.c:10924
 rtnl_unlock net/core/rtnetlink.c:152 [inline]
 rtnl_net_unlock net/core/rtnetlink.c:209 [inline]
 rtnl_dellink+0x484/0x680 net/core/rtnetlink.c:3526
 rtnetlink_rcv_msg+0x61c/0x918 net/core/rtnetlink.c:6901
 netlink_rcv_skb+0x1dc/0x398 net/netlink/af_netlink.c:2542
 rtnetlink_rcv+0x34/0x50 net/core/rtnetlink.c:6928
 netlink_unicast_kernel net/netlink/af_netlink.c:1321 [inline]
 netlink_unicast+0x618/0x838 net/netlink/af_netlink.c:1347
 netlink_sendmsg+0x5fc/0x8b0 net/netlink/af_netlink.c:1891
 sock_sendmsg_nosec net/socket.c:711 [inline]
 __sock_sendmsg net/socket.c:726 [inline]
 ____sys_sendmsg+0x410/0x708 net/socket.c:2583
 ___sys_sendmsg+0x178/0x1d8 net/socket.c:2637
 __sys_sendmsg net/socket.c:2669 [inline]
 __do_sys_sendmsg net/socket.c:2674 [inline]
 __se_sys_sendmsg net/socket.c:2672 [inline]
 __arm64_sys_sendmsg+0x12c/0x1c8 net/socket.c:2672
 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
 invoke_syscall+0x90/0x278 arch/arm64/kernel/syscall.c:49
 el0_svc_common+0x13c/0x250 arch/arm64/kernel/syscall.c:132
 do_el0_svc+0x54/0x70 arch/arm64/kernel/syscall.c:151
 el0_svc+0x4c/0xa8 arch/arm64/kernel/entry-common.c:744
 el0t_64_sync_handler+0x78/0x108 arch/arm64/kernel/entry-common.c:762
 el0t_64_sync+0x198/0x1a0 arch/arm64/kernel/entry.S:600

The buggy address belongs to the object at ffff0000d768c000
 which belongs to the cache kmalloc-cg-4k of size 4096
The buggy address is located 224 bytes inside of
 freed 4096-byte region [ffff0000d768c000, ffff0000d768d000)

The buggy address belongs to the physical page:
page: refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x117688
head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
memcg:ffff0000c77ef981
flags: 0xbfffe0000000040(head|node=0|zone=2|lastcpupid=0x1ffff)
page_type: f5(slab)
raw: 0bfffe0000000040 ffff0000c000f500 dead000000000100 dead000000000122
raw: 0000000000000000 0000000000040004 00000001f5000000 ffff0000c77ef981
head: 0bfffe0000000040 ffff0000c000f500 dead000000000100 dead000000000122
head: 0000000000000000 0000000000040004 00000001f5000000 ffff0000c77ef981
head: 0bfffe0000000003 fffffdffc35da201 ffffffffffffffff 0000000000000000
head: 0000000000000008 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff0000d768bf80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff0000d768c000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff0000d768c080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                       ^
 ffff0000d768c100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff0000d768c180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb

Fixes: 8c55facecd ("net: linkwatch: only report IF_OPER_LOWERLAYERDOWN if iflink is actually down")
Reported-by: syzkaller <syzkaller@googlegroups.com>
Suggested-by: Jakub Kicinski <kuba@kernel.org>
Link: https://lore.kernel.org/netdev/20250102174400.085fd8ac@kernel.org/ [1]
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://patch.msgid.link/20250106071911.64355-1-kuniyu@amazon.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
History 2025-01-17 13:36:13 +01:00
..
bpf_sk_storage.c bpf: Add length check for SK_DIAG_BPF_STORAGE_REQ_MAP_FD parsing 2023-07-27 10:07:56 -07:00
datagram.c net: fix rc7's __skb_datagram_iter() 2024-07-18 13:21:13 +02:00
dev.c net: reenable NETIF_F_IPV6_CSUM offload for BIG TCP packets 2025-01-09 13:32:02 +01:00
dev.h net: fix removing a namespace with conflicting altnames 2024-01-31 16:19:01 -08:00
dev_addr_lists.c net: extract a few internals from netdevice.h 2022-04-07 20:32:09 -07:00
dev_addr_lists_test.c kunit: Use KUNIT_EXPECT_MEMEQ macro 2022-10-27 02:40:14 -06:00
dev_ioctl.c net: omit ndo_hwtstamp_get() call when possible in dev_set_hwtstamp_phylib() 2023-08-06 13:25:10 +01:00
drop_monitor.c drop_monitor: replace spin_lock by raw_spin_lock 2024-06-27 13:49:01 +02:00
dst.c net: do not delay dst_entries_add() in dst_release() 2024-10-17 15:24:28 +02:00
dst_cache.c ipv6: introduce dst_rt6_info() helper 2024-12-14 19:59:35 +01:00
failover.c net: failover: use IFF_NO_ADDRCONF flag to prevent ipv6 addrconf 2022-12-12 15:18:25 -08:00
fib_notifier.c net: fib_notifier: propagate extack down to the notifier block callback 2019-10-04 11:10:56 -07:00
fib_rules.c fib: expand fib_rule_policy 2021-12-16 07:18:35 -08:00
filter.c bpf: Check negative offsets in __bpf_skb_min_len() 2025-01-02 10:32:00 +01:00
flow_dissector.c net: flow_dissector: use DEBUG_NET_WARN_ON_ONCE 2024-08-03 08:54:05 +02:00
flow_offload.c tc: flower: Enable offload support IPSEC SPI field. 2023-08-02 10:09:32 +01:00
gen_estimator.c net: use unrcu_pointer() helper 2024-12-09 10:32:10 +01:00
gen_stats.c net: Remove the obsolte u64_stats_fetch_*_irq() users (net). 2022-10-28 20:13:54 -07:00
gro.c net: Add netif_get_gro_max_size helper for GRO 2024-10-10 11:57:16 +02:00
gro_cells.c net: drop the weight argument from netif_napi_add 2022-09-28 18:57:14 -07:00
gso.c net: move gso declarations and functions to their own files 2023-06-10 00:11:41 -07:00
hwbm.c net: hwbm: Make the hwbm_pool lock a mutex 2019-06-09 19:40:10 -07:00
link_watch.c ipvlan: Fix use-after-free in ipvlan_get_iflink(). 2025-01-17 13:36:13 +01:00
lwt_bpf.c lwt: Fix return values of BPF xmit ops 2023-08-18 16:05:26 +02:00
lwtunnel.c xfrm: lwtunnel: squelch kernel warning in case XFRM encap type is not available 2022-10-12 10:45:51 +02:00
Makefile net: move gso declarations and functions to their own files 2023-06-10 00:11:41 -07:00
neighbour.c net/neighbor: clear error in case strict check is not set 2024-12-14 20:00:09 +01:00
net-procfs.c net-sysfs: display two backlog queue len separately 2023-03-22 12:03:52 +01:00
net-sysfs.c ethtool: check device is present when getting link settings 2024-09-04 13:28:26 +02:00
net-sysfs.h net-sysfs: add netdev_change_owner() 2020-02-26 20:07:25 -08:00
net-traces.c udp6: add a missing call into udp_fail_queue_rcv_skb tracepoint 2023-07-07 09:16:52 +01:00
net_namespace.c net: defer final 'struct net' free in netns dismantle 2024-12-19 18:11:28 +01:00
netclassid_cgroup.c core: Variable type completion 2022-08-31 09:40:34 +01:00
netdev-genl-gen.c net: ynl: prefix uAPI header include with uapi/ 2023-05-26 10:30:14 +01:00
netdev-genl-gen.h net: ynl: prefix uAPI header include with uapi/ 2023-05-26 10:30:14 +01:00
netdev-genl.c netdev-genl: use struct genl_info for reply construction 2023-08-15 15:01:03 -07:00
netevent.c net: core: Correct function name netevent_unregister_notifier() in the kerneldoc 2021-03-28 17:56:56 -07:00
netpoll.c netpoll: Use rcu_access_pointer() in __netpoll_setup 2024-12-14 20:00:10 +01:00
netprio_cgroup.c bpf, cgroups: Fix cgroup v2 fallback on v1/v2 mixed mode 2021-09-13 16:35:58 -07:00
of_net.c net: Explicitly include correct DT includes 2023-07-27 20:33:16 -07:00
page_pool.c net: page_pool: add missing free_percpu when page_pool_init fail 2023-11-20 11:59:34 +01:00
pktgen.c kthread: add kthread_stop_put 2024-06-12 11:12:52 +02:00
ptp_classifier.c ptp: Add generic PTP is_sync() function 2022-03-07 11:31:34 +00:00
request_sock.c tcp: make sure init the accept_queue's spinlocks once 2024-01-31 16:19:00 -08:00
rtnetlink.c net: fix crash when config small gso_max_size/gso_ipv4_max_size 2024-11-08 16:28:18 +01:00
scm.c io_uring/unix: drop usage of io_uring socket 2024-03-26 18:19:09 -04:00
secure_seq.c tcp: Fix data-races around sysctl knobs related to SYN option. 2022-07-20 10:14:49 +01:00
selftests.c net: core: constify mac addrs in selftests 2021-10-24 13:59:44 +01:00
skbuff.c net: core: reject skb_copy(_expand) for fraglist GSO skbs 2024-05-17 12:02:06 +02:00
skmsg.c tcp_bpf: Add sk_rmem_alloc related logic for tcp_bpf ingress redirection 2025-01-02 10:32:00 +01:00
sock.c net: restrict SO_REUSEPORT to inet sockets 2025-01-09 13:32:02 +01:00
sock_destructor.h skb_expand_head() adjust skb->truesize incorrectly 2021-10-22 12:35:51 -07:00
sock_diag.c net: use unrcu_pointer() helper 2024-12-09 10:32:10 +01:00
sock_map.c bpf, sockmap: Fix update element with same 2024-12-19 18:11:25 +01:00
sock_reuseport.c soreuseport: Fix socket selection for SO_INCOMING_CPU. 2022-10-25 11:35:16 +02:00
stream.c net: Return error from sk_stream_wait_connect() if sk_wait_event() fails 2024-01-01 12:42:30 +00:00
sysctl_net_core.c net: make SK_MEMORY_PCPU_RESERV tunable 2024-05-02 16:32:36 +02:00
timestamping.c net: Introduce a new MII time stamping interface. 2019-12-25 19:51:33 -08:00
tso.c net: tso: inline tso_count_descs() 2022-12-12 15:04:39 -08:00
utils.c net: core: inet[46]_pton strlen len types 2022-11-01 21:14:39 -07:00
xdp.c xdp: fix invalid wait context of page_pool_destroy() 2024-08-03 08:53:44 +02:00