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BUG: KASAN: slab-use-after-free in __ethtool_get_link_ksettings+0x5e/0x170
Read of size 8 at addr ffff8881bbcf42f0 by task syz.0.13236/18043

CPU: 1 UID: 0 PID: 18043 Comm: syz.0.13236 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
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
 ib_setup_port_attrs+0x26e/0x2140
 add_one_compat_dev+0x448/0x650
 rdma_dev_init_net+0x243/0x2f0
 ops_init+0x35c/0x5c0
 setup_net+0x118/0x340
 copy_net_ns+0x3e2/0x570
 create_new_namespaces+0x3e7/0x6a0
 unshare_nsproxy_namespaces+0x11a/0x160
 ksys_unshare+0x4f4/0x900
 __x64_sys_unshare+0x38/0x50
 do_syscall_64+0xe2/0xf80
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f055559acb9
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f05563cb028 EFLAGS: 00000246 ORIG_RAX: 0000000000000110
RAX: ffffffffffffffda RBX: 00007f0555816090 RCX: 00007f055559acb9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 000000006a040000
RBP: 00007f0555608bf7 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f0555816128 R14: 00007f0555816090 R15: 00007ffd8a1ec948
 </TASK>

Allocated by task 5837:
 kasan_save_track+0x3e/0x80
 __kasan_kmalloc+0x93/0xb0
 __kvmalloc_node_noprof+0x59a/0x8d0
 alloc_netdev_mqs+0xa6/0x11b0
 rtnl_create_link+0x31f/0xd70
 rtnl_newlink_create+0x277/0xb70
 rtnl_newlink+0x1666/0x1be0
 rtnetlink_rcv_msg+0x7d5/0xbe0
 netlink_rcv_skb+0x232/0x4b0
 netlink_unicast+0x80f/0x9b0
 netlink_sendmsg+0x813/0xb40
 __sock_sendmsg+0x21c/0x270
 __sys_sendto+0x3c0/0x550
 __x64_sys_sendto+0xde/0x100
 do_syscall_64+0xe2/0xf80
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 18053:
 kasan_save_track+0x3e/0x80
 kasan_save_free_info+0x46/0x50
 __kasan_slab_free+0x5c/0x80
 kfree+0x1be/0x650
 device_release+0x9e/0x1d0
 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
 __sock_sendmsg+0x21c/0x270
 ____sys_sendmsg+0x4d7/0x810
 ___sys_sendmsg+0x2a5/0x360
 __x64_sys_sendmsg+0x1bd/0x2a0
 do_syscall_64+0xe2/0xf80
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff8881bbcf4000
 which belongs to the cache kmalloc-cg-4k of size 4096
The buggy address is located 752 bytes inside of
 freed 4096-byte region [ffff8881bbcf4000, ffff8881bbcf5000)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1bbcf0
head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
memcg:ffff888173445381
flags: 0x57ff00000000040(head|node=1|zone=2|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 057ff00000000040 ffff88810004b500 dead000000000100 dead000000000122
raw: 0000000000000000 0000000000040004 00000000f5000000 ffff888173445381
head: 057ff00000000040 ffff88810004b500 dead000000000100 dead000000000122
head: 0000000000000000 0000000000040004 00000000f5000000 ffff888173445381
head: 057ff00000000003 ffffea0006ef3c01 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 5837, tgid 5837 (syz-executor), ts 66333579629, free_ts 42696019712
 post_alloc_hook+0x228/0x280
 get_page_from_freelist+0x24dc/0x2580
 __alloc_frozen_pages_noprof+0x18d/0x380
 alloc_pages_mpol+0x232/0x4a0
 allocate_slab+0x86/0x3a0
 ___slab_alloc+0xd82/0x1760
 __slab_alloc+0x65/0x100
 __kmalloc_node_track_caller_noprof+0x5b7/0x7f0
 kmemdup_noprof+0x2b/0x70
 __addrconf_sysctl_register+0xa7/0x4d0
 addrconf_sysctl_register+0x168/0x1c0
 ipv6_add_dev+0xd26/0x13a0
 addrconf_notify+0x771/0x1050
 notifier_call_chain+0x19d/0x3a0
 register_netdevice+0x1637/0x1ae0
 virt_wifi_newlink+0x428/0x860
page last free pid 5593 tgid 5593 stack trace:
 __free_frozen_pages+0xbb0/0xd10
 __put_partials+0x146/0x170
 __slab_free+0x294/0x320
 qlist_free_all+0x97/0x100
 kasan_quarantine_reduce+0x148/0x160
 __kasan_slab_alloc+0x22/0x80
 kmem_cache_alloc_noprof+0x370/0x6e0
 proc_reg_open+0x1f4/0x540
 do_dentry_open+0x7ce/0x1420
 vfs_open+0x3b/0x340
 path_openat+0x3486/0x3e20
 do_filp_open+0x22d/0x490
 do_sys_openat2+0x12f/0x220
 __x64_sys_openat+0x138/0x170
 do_syscall_64+0xe2/0xf80
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff8881bbcf4180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8881bbcf4200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff8881bbcf4280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                             ^
 ffff8881bbcf4300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8881bbcf4380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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