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BUG: KASAN: slab-use-after-free in __ethtool_get_link_ksettings+0x5e/0x170
Read of size 8 at addr ffff88816f48c2f0 by task kworker/0:14/9752

CPU: 0 UID: 0 PID: 9752 Comm: kworker/0:14 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_report+0xba/0x230
 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+0xb6e/0x18c0
 worker_thread+0xa53/0xfc0
 kthread+0x388/0x470
 ret_from_fork+0x51e/0xb90
 ret_from_fork_asm+0x1a/0x30
 </TASK>

Allocated by task 5806:
 kasan_save_track+0x3e/0x80
 __kasan_kmalloc+0x93/0xb0
 __kvmalloc_node_noprof+0x528/0x8a0
 alloc_netdev_mqs+0xa6/0x11b0
 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+0x80f/0x9b0
 netlink_sendmsg+0x813/0xb40
 __sys_sendto+0x672/0x710
 __x64_sys_sendto+0xde/0x100
 do_syscall_64+0x14d/0xf80
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 17708:
 kasan_save_track+0x3e/0x80
 kasan_save_free_info+0x46/0x50
 __kasan_slab_free+0x5c/0x80
 kfree+0x1c1/0x630
 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+0x80f/0x9b0
 netlink_sendmsg+0x813/0xb40
 ____sys_sendmsg+0x972/0x9f0
 ___sys_sendmsg+0x2a5/0x360
 __x64_sys_sendmsg+0x1bd/0x2a0
 do_syscall_64+0x14d/0xf80
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff88816f48c000
 which belongs to the cache kmalloc-cg-4k of size 4096
The buggy address is located 752 bytes inside of
 freed 4096-byte region [ffff88816f48c000, ffff88816f48d000)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x16f488
head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
memcg:ffff88816f96e441
flags: 0x57ff00000000040(head|node=1|zone=2|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 057ff00000000040 ffff88810005d500 dead000000000100 dead000000000122
raw: 0000000000000000 0000000800040004 00000000f5000000 ffff88816f96e441
head: 057ff00000000040 ffff88810005d500 dead000000000100 dead000000000122
head: 0000000000000000 0000000800040004 00000000f5000000 ffff88816f96e441
head: 057ff00000000003 ffffea0005bd2201 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 5806, tgid 5806 (syz-executor), ts 55874322232, free_ts 55782170450
 post_alloc_hook+0x231/0x280
 get_page_from_freelist+0x24dc/0x2580
 __alloc_frozen_pages_noprof+0x18d/0x380
 allocate_slab+0x77/0x660
 refill_objects+0x331/0x3c0
 __pcs_replace_empty_main+0x2e6/0x730
 __kmalloc_cache_noprof+0x392/0x660
 ipv6_add_dev+0x6aa/0x13a0
 addrconf_notify+0x771/0x1050
 notifier_call_chain+0x1be/0x400
 register_netdevice+0x173a/0x1cf0
 veth_newlink+0x67b/0xb70
 rtnl_newlink_create+0x329/0xb70
 rtnl_newlink+0x166a/0x1bb0
 rtnetlink_rcv_msg+0x7d5/0xbe0
 netlink_rcv_skb+0x232/0x4b0
page last free pid 5806 tgid 5806 stack trace:
 __free_frozen_pages+0xc2b/0xdb0
 __slab_free+0x263/0x2b0
 qlist_free_all+0x97/0x100
 kasan_quarantine_reduce+0x148/0x160
 __kasan_slab_alloc+0x22/0x80
 __kmalloc_cache_noprof+0x2ba/0x660
 kset_create_and_add+0x5a/0x170
 netdev_register_kobject+0x1a2/0x310
 register_netdevice+0x12c0/0x1cf0
 veth_newlink+0x67b/0xb70
 rtnl_newlink_create+0x329/0xb70
 rtnl_newlink+0x166a/0x1bb0
 rtnetlink_rcv_msg+0x7d5/0xbe0
 netlink_rcv_skb+0x232/0x4b0
 netlink_unicast+0x80f/0x9b0
 netlink_sendmsg+0x813/0xb40

Memory state around the buggy address:
 ffff88816f48c180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88816f48c200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88816f48c280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                             ^
 ffff88816f48c300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88816f48c380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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