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BUG: KASAN: slab-use-after-free in __ethtool_get_link_ksettings+0x6e/0x190
Read of size 8 at addr ffff8881b3f282e8 by task syz.7.624/8358

CPU: 1 UID: 0 PID: 8358 Comm: syz.7.624 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/0xfa0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f46ea98f749
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:00007f46eb82d038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f46eabe5fa0 RCX: 00007f46ea98f749
RDX: 0000000004040084 RSI: 0000200000000480 RDI: 0000000000000006
RBP: 00007f46eaa13f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f46eabe6038 R14: 00007f46eabe5fa0 R15: 00007ffc173933a8
 </TASK>

Allocated by task 5810:
 kasan_save_track+0x3e/0x80
 __kasan_kmalloc+0x93/0xb0
 __kvmalloc_node_noprof+0x5cd/0x910
 alloc_netdev_mqs+0xa6/0x11b0
 rtnl_create_link+0x31f/0xd10
 rtnl_newlink_create+0x25c/0xb00
 rtnl_newlink+0x16e4/0x1c80
 rtnetlink_rcv_msg+0x7cf/0xb70
 netlink_rcv_skb+0x208/0x470
 netlink_unicast+0x82f/0x9e0
 netlink_sendmsg+0x805/0xb30
 __sock_sendmsg+0x21c/0x270
 __sys_sendto+0x3bd/0x520
 __x64_sys_sendto+0xde/0x100
 do_syscall_64+0xfa/0xfa0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 12:
 kasan_save_track+0x3e/0x80
 __kasan_save_free_info+0x46/0x50
 __kasan_slab_free+0x5c/0x80
 kfree+0x19a/0x6d0
 device_release+0x9c/0x1c0
 kobject_put+0x22b/0x480
 netdev_run_todo+0xd2e/0xea0
 default_device_exit_batch+0x81e/0x890
 ops_undo_list+0x525/0x990
 cleanup_net+0x4d8/0x820
 process_scheduled_works+0xae1/0x17b0
 worker_thread+0x8a0/0xda0
 kthread+0x711/0x8a0
 ret_from_fork+0x4bc/0x870
 ret_from_fork_asm+0x1a/0x30

The buggy address belongs to the object at ffff8881b3f28000
 which belongs to the cache kmalloc-cg-4k of size 4096
The buggy address is located 744 bytes inside of
 freed 4096-byte region [ffff8881b3f28000, ffff8881b3f29000)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1b3f28
head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0x57ff00000000040(head|node=1|zone=2|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 057ff00000000040 ffff88810004b500 dead000000000122 0000000000000000
raw: 0000000000000000 0000000000040004 00000000f5000000 0000000000000000
head: 057ff00000000040 ffff88810004b500 dead000000000122 0000000000000000
head: 0000000000000000 0000000000040004 00000000f5000000 0000000000000000
head: 057ff00000000003 ffffea0006cfca01 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 0xd60c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_RETRY_MAYFAIL|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 5810, tgid 5810 (syz-executor), ts 55364239520, free_ts 20082851186
 post_alloc_hook+0x240/0x2a0
 get_page_from_freelist+0x2365/0x2440
 __alloc_frozen_pages_noprof+0x181/0x370
 alloc_pages_mpol+0x232/0x4a0
 allocate_slab+0x96/0x350
 ___slab_alloc+0xf56/0x1990
 __slab_alloc+0x65/0x100
 __kvmalloc_node_noprof+0x6ba/0x910
 alloc_netdev_mqs+0xa6/0x11b0
 rtnl_create_link+0x31f/0xd10
 rtnl_newlink_create+0x25c/0xb00
 rtnl_newlink+0x16e4/0x1c80
 rtnetlink_rcv_msg+0x7cf/0xb70
 netlink_rcv_skb+0x208/0x470
 netlink_unicast+0x82f/0x9e0
 netlink_sendmsg+0x805/0xb30
page last free pid 1 tgid 1 stack trace:
 __free_frozen_pages+0xbc4/0xd30
 free_contig_range+0x1bd/0x4a0
 destroy_args+0x69/0x660
 debug_vm_pgtable+0x39f/0x3b0
 do_one_initcall+0x236/0x820
 do_initcall_level+0x104/0x190
 do_initcalls+0x59/0xa0
 kernel_init_freeable+0x334/0x4b0
 kernel_init+0x1d/0x1d0
 ret_from_fork+0x4bc/0x870
 ret_from_fork_asm+0x1a/0x30

Memory state around the buggy address:
 ffff8881b3f28180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8881b3f28200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff8881b3f28280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                          ^
 ffff8881b3f28300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8881b3f28380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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