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BUG: KASAN: slab-use-after-free in __ethtool_get_link_ksettings+0x6e/0x190
Read of size 8 at addr ffff88810a6ba2e8 by task kworker/1:0/24

CPU: 1 UID: 0 PID: 24 Comm: kworker/1:0 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Workqueue: events smc_ib_port_event_work
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250
 print_report+0xca/0x240
 kasan_report+0x118/0x150
 __ethtool_get_link_ksettings+0x6e/0x190
 ib_get_eth_speed+0x15e/0x7b0
 rxe_query_port+0x93/0x3b0
 ib_query_port+0x170/0x830
 smc_ib_port_event_work+0x15a/0x940
 process_scheduled_works+0xae1/0x17b0
 worker_thread+0x8a0/0xda0
 kthread+0x711/0x8a0
 ret_from_fork+0x3fc/0x770
 ret_from_fork_asm+0x1a/0x30
 </TASK>

Allocated by task 6198:
 kasan_save_track+0x3e/0x80
 __kasan_kmalloc+0x93/0xb0
 __kvmalloc_node_noprof+0x30d/0x5f0
 alloc_netdev_mqs+0xa3/0x1170
 rtnl_create_link+0x31f/0xd10
 rtnl_newlink_create+0x25c/0xb00
 rtnl_newlink+0x16d6/0x1c70
 rtnetlink_rcv_msg+0x7cf/0xb70
 netlink_rcv_skb+0x208/0x470
 netlink_unicast+0x82f/0x9e0
 netlink_sendmsg+0x805/0xb30
 __sock_sendmsg+0x21c/0x270
 __sys_sendto+0x3bd/0x520
 __x64_sys_sendto+0xde/0x100
 do_syscall_64+0xfa/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 13:
 kasan_save_track+0x3e/0x80
 kasan_save_free_info+0x46/0x50
 __kasan_slab_free+0x5b/0x80
 kfree+0x18e/0x440
 device_release+0x9c/0x1c0
 kobject_put+0x22b/0x480
 netdev_run_todo+0xd2e/0xea0
 default_device_exit_batch+0x81e/0x890
 ops_undo_list+0x525/0x990
 cleanup_net+0x4c5/0x800
 process_scheduled_works+0xae1/0x17b0
 worker_thread+0x8a0/0xda0
 kthread+0x711/0x8a0
 ret_from_fork+0x3fc/0x770
 ret_from_fork_asm+0x1a/0x30

The buggy address belongs to the object at ffff88810a6ba000
 which belongs to the cache kmalloc-cg-4k of size 4096
The buggy address is located 744 bytes inside of
 freed 4096-byte region [ffff88810a6ba000, ffff88810a6bb000)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x10a6b8
head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
memcg:ffff888106ff72c1
ksm flags: 0x57ff00000000040(head|node=1|zone=2|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 057ff00000000040 ffff88801a44b500 ffffea0004232a00 0000000000000003
raw: 0000000000000000 0000000000040004 00000000f5000000 ffff888106ff72c1
head: 057ff00000000040 ffff88801a44b500 ffffea0004232a00 0000000000000003
head: 0000000000000000 0000000000040004 00000000f5000000 ffff888106ff72c1
head: 057ff00000000003 ffffea000429ae01 00000000ffffffff 00000000ffffffff
head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000008
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 6198, tgid 6198 (syz-executor), ts 115560628569, free_ts 115553398282
 post_alloc_hook+0x240/0x2a0
 get_page_from_freelist+0x21e4/0x22c0
 __alloc_frozen_pages_noprof+0x181/0x370
 alloc_pages_mpol+0x232/0x4a0
 allocate_slab+0x8a/0x370
 ___slab_alloc+0xbeb/0x1410
 __kmalloc_noprof+0x305/0x4f0
 __register_sysctl_table+0x72/0x1340
 __addrconf_sysctl_register+0x328/0x4c0
 addrconf_sysctl_register+0x168/0x1c0
 ipv6_add_dev+0xd46/0x1370
 addrconf_notify+0x794/0x1010
 notifier_call_chain+0x1b6/0x3e0
 register_netdevice+0x1608/0x1ae0
 virt_wifi_newlink+0x428/0x860
 rtnl_newlink_create+0x310/0xb00
page last free pid 6198 tgid 6198 stack trace:
 __free_frozen_pages+0xbc4/0xd30
 __put_partials+0x156/0x1a0
 put_cpu_partial+0x17c/0x250
 __slab_free+0x2d5/0x3c0
 qlist_free_all+0x97/0x140
 kasan_quarantine_reduce+0x148/0x160
 __kasan_slab_alloc+0x22/0x80
 __kmalloc_cache_noprof+0x1be/0x3d0
 dropmon_net_event+0x221/0x2b0
 notifier_call_chain+0x1b6/0x3e0
 register_netdevice+0x1608/0x1ae0
 veth_newlink+0x5cc/0xa50
 rtnl_newlink_create+0x310/0xb00
 rtnl_newlink+0x16d6/0x1c70
 rtnetlink_rcv_msg+0x7cf/0xb70
 netlink_rcv_skb+0x208/0x470

Memory state around the buggy address:
 ffff88810a6ba180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88810a6ba200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88810a6ba280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                          ^
 ffff88810a6ba300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88810a6ba380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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