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BUG: KASAN: use-after-free in __ethtool_get_link_ksettings+0x6e/0x190
Read of size 8 at addr ffff8881240002e8 by task syz.3.1762/10131

CPU: 1 UID: 0 PID: 10131 Comm: syz.3.1762 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+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
 fill_port_info+0x1b9/0x5b0
 nldev_port_get_dumpit+0x57f/0x8a0
 netlink_dump+0x6e4/0xe90
 __netlink_dump_start+0x5cb/0x7e0
 rdma_nl_rcv+0x749/0x980
 netlink_unicast+0x82f/0x9e0
 netlink_sendmsg+0x805/0xb30
 __sock_sendmsg+0x21c/0x270
 ____sys_sendmsg+0x505/0x830
 ___sys_sendmsg+0x21f/0x2a0
 __x64_sys_sendmsg+0x19b/0x260
 do_syscall_64+0xfa/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7ff25a78ec29
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ff25b60a038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007ff25a9d5fa0 RCX: 00007ff25a78ec29
RDX: 0000000000000000 RSI: 0000200000000480 RDI: 0000000000000004
RBP: 00007ff25a811e41 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ff25a9d6038 R14: 00007ff25a9d5fa0 R15: 00007ffdb561d618
 </TASK>

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff888124006000 pfn:0x124000
flags: 0x57ff00000000000(node=1|zone=2|lastcpupid=0x7ff)
page_type: f0(buddy)
raw: 057ff00000000000 ffffea00048d5208 ffffea0004465608 0000000000000000
raw: ffff888124006000 0000000000000003 00000000f0000000 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as freed
page last allocated via order 3, migratetype Unmovable, gfp_mask 0xd60c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_RETRY_MAYFAIL|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 5893, tgid 5893 (syz-executor), ts 60839593001, free_ts 172423619517
 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/0x1420
 __kvmalloc_node_noprof+0x429/0x5f0
 alloc_netdev_mqs+0xa3/0x11b0
 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
page last free pid 9751 tgid 9749 stack trace:
 __free_frozen_pages+0xbc4/0xd30
 __slab_free+0x303/0x3c0
 qlist_free_all+0x97/0x140
 kasan_quarantine_reduce+0x148/0x160
 __kasan_slab_alloc+0x22/0x80
 __kvmalloc_node_noprof+0x2b0/0x5f0
 btf_parse_type_sec+0x5ae/0x24a0
 btf_new_fd+0x40e/0xc90
 __sys_bpf+0x3e5/0x850
 __x64_sys_bpf+0x7c/0x90
 do_syscall_64+0xfa/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff888124000180: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888124000200: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff888124000280: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                                          ^
 ffff888124000300: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888124000380: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
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