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BUG: KASAN: use-after-free in __ethtool_get_link_ksettings+0x5e/0x170
Read of size 8 at addr ffff8881a56c82f0 by task syz.0.7390/2195

CPU: 0 UID: 0 PID: 2195 Comm: syz.0.7390 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+0x294/0x2380
 add_one_compat_dev+0x448/0x650
 rdma_dev_init_net+0x243/0x2f0
 ops_init+0x35c/0x5c0
 setup_net+0x118/0x340
 copy_net_ns+0x50e/0x730
 create_new_namespaces+0x3e7/0x6a0
 unshare_nsproxy_namespaces+0x11a/0x160
 ksys_unshare+0x51d/0x930
 __x64_sys_unshare+0x38/0x50
 do_syscall_64+0x14d/0xf80
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f4ff459c799
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:00007f4ff54ac028 EFLAGS: 00000246 ORIG_RAX: 0000000000000110
RAX: ffffffffffffffda RBX: 00007f4ff4816090 RCX: 00007f4ff459c799
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 000000006a040000
RBP: 00007f4ff4632c99 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f4ff4816128 R14: 00007f4ff4816090 R15: 00007ffe3edd4448
 </TASK>

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff8881a56ca800 pfn:0x1a56c8
flags: 0x57ff00000000000(node=1|zone=2|lastcpupid=0x7ff)
raw: 057ff00000000000 ffffea0006050f08 ffff888121040f40 0000000000000000
raw: ffff8881a56ca800 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as freed
page last allocated via order 2, migratetype Unmovable, gfp_mask 0x446dc0(GFP_KERNEL_ACCOUNT|__GFP_ZERO|__GFP_NOWARN|__GFP_RETRY_MAYFAIL|__GFP_COMP), pid 11080, tgid 11079 (syz.2.1332), ts 161845104754, free_ts 599858838625
 post_alloc_hook+0x231/0x280
 get_page_from_freelist+0x24dc/0x2580
 __alloc_frozen_pages_noprof+0x18d/0x380
 alloc_pages_mpol+0x232/0x4a0
 ___kmalloc_large_node+0x4e/0x150
 __kmalloc_large_node_noprof+0x18/0x90
 __kvmalloc_node_noprof+0x7b/0x8a0
 alloc_netdev_mqs+0xa6/0x11b0
 ieee80211_if_add+0x482/0x13a0
 ieee80211_register_hw+0x36a3/0x4200
 mac80211_hwsim_new_radio+0x2f97/0x5330
 hwsim_new_radio_nl+0xf35/0x1bd0
 genl_family_rcv_msg_doit+0x22a/0x330
 genl_rcv_msg+0x61c/0x7a0
 netlink_rcv_skb+0x232/0x4b0
 genl_rcv+0x28/0x40
page last free pid 2199 tgid 2198 stack trace:
 __free_frozen_pages+0xc2b/0xdb0
 device_release+0x9e/0x1d0
 kobject_put+0x228/0x560
 netdev_run_todo+0xc75/0xde0
 nl80211_post_doit+0x21d/0x320
 genl_family_rcv_msg_doit+0x26b/0x330
 genl_rcv_msg+0x61c/0x7a0
 netlink_rcv_skb+0x232/0x4b0
 genl_rcv+0x28/0x40
 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

Memory state around the buggy address:
 ffff8881a56c8180: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8881a56c8200: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff8881a56c8280: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                                             ^
 ffff8881a56c8300: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8881a56c8380: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
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