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BUG: KASAN: slab-use-after-free in __ethtool_get_link_ksettings+0x5e/0x170
Read of size 8 at addr ffff88811d3f42f0 by task kworker/0:2/713

CPU: 0 UID: 0 PID: 713 Comm: kworker/0:2 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+0xe8/0x150
 print_address_description+0x55/0x1e0
 print_report+0x58/0x70
 kasan_report+0x117/0x150
 __ethtool_get_link_ksettings+0x5e/0x170
 ib_get_eth_speed+0x180/0x7f0
 rxe_query_port+0x93/0x3d0
 ib_query_port+0x170/0x830
 smc_ib_port_event_work+0x15a/0x940
 process_scheduled_works+0xb5d/0x1860
 worker_thread+0xa53/0xfc0
 kthread+0x388/0x470
 ret_from_fork+0x514/0xb70
 ret_from_fork_asm+0x1a/0x30
 </TASK>

Allocated by task 5715:
 kasan_save_track+0x3e/0x80
 __kasan_kmalloc+0x93/0xb0
 __kvmalloc_node_noprof+0x528/0x8a0
 alloc_netdev_mqs+0xa8/0x1210
 rtnl_create_link+0x31f/0xd70
 rtnl_newlink_create+0x277/0xb70
 rtnl_newlink+0x166a/0x1bb0
 rtnetlink_rcv_msg+0x7d5/0xbe0
 netlink_rcv_skb+0x232/0x4b0
 netlink_unicast+0x75c/0x8e0
 netlink_sendmsg+0x813/0xb40
 __sys_sendto+0x672/0x710
 __x64_sys_sendto+0xde/0x100
 do_syscall_64+0x15f/0xf80
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 22210:
 kasan_save_track+0x3e/0x80
 kasan_save_free_info+0x46/0x50
 __kasan_slab_free+0x5c/0x80
 kfree+0x1c5/0x640
 device_release+0xc4/0x1f0
 kobject_put+0x228/0x560
 netdev_run_todo+0xc75/0xde0
 rtnl_dellink+0x6a7/0x820
 rtnetlink_rcv_msg+0x7d5/0xbe0
 netlink_rcv_skb+0x232/0x4b0
 netlink_unicast+0x75c/0x8e0
 netlink_sendmsg+0x813/0xb40
 ____sys_sendmsg+0x972/0x9f0
 ___sys_sendmsg+0x2a5/0x360
 __x64_sys_sendmsg+0x1bd/0x2a0
 do_syscall_64+0x15f/0xf80
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff88811d3f4000
 which belongs to the cache kmalloc-cg-4k of size 4096
The buggy address is located 752 bytes inside of
 freed 4096-byte region [ffff88811d3f4000, ffff88811d3f5000)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x11d3f0
head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
memcg:ffff88811d3f1011
flags: 0x17ff00000000040(head|node=0|zone=2|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 017ff00000000040 ffff88810005d500 dead000000000100 dead000000000122
raw: 0000000000000000 0000200000040004 00000000f5000000 ffff88811d3f1011
head: 017ff00000000040 ffff88810005d500 dead000000000100 dead000000000122
head: 0000000000000000 0000200000040004 00000000f5000000 ffff88811d3f1011
head: 017ff00000000003 fffffffffffffe01 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 5715, tgid 5715 (syz-executor), ts 71654605870, free_ts 68413408186
 post_alloc_hook+0x231/0x280
 get_page_from_freelist+0x24ba/0x2540
 __alloc_frozen_pages_noprof+0x18d/0x380
 allocate_slab+0x77/0x660
 refill_objects+0x339/0x3d0
 __pcs_replace_empty_main+0x321/0x720
 __kmalloc_noprof+0x474/0x760
 __register_sysctl_table+0x72/0x1340
 __addrconf_sysctl_register+0x331/0x4d0
 addrconf_sysctl_register+0x168/0x1c0
 ipv6_add_dev+0xd26/0x13a0
 addrconf_notify+0x771/0x1050
 notifier_call_chain+0x1ad/0x3d0
 register_netdevice+0x18c9/0x1ec0
 virt_wifi_newlink+0x3e8/0x820
 rtnl_newlink_create+0x329/0xb70
page last free pid 5646 tgid 5646 stack trace:
 __free_frozen_pages+0xbc7/0xd30
 vfree+0x1d1/0x2f0
 kcov_close+0x28/0x50
 __fput+0x44f/0xa60
 task_work_run+0x1d9/0x270
 do_exit+0x70f/0x22c0
 do_group_exit+0x21b/0x2d0
 get_signal+0x1284/0x1330
 arch_do_signal_or_restart+0xbc/0x830
 exit_to_user_mode_loop+0x86/0x480
 do_syscall_64+0x33e/0xf80
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff88811d3f4180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88811d3f4200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88811d3f4280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                             ^
 ffff88811d3f4300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88811d3f4380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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