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BUG: KFENCE: use-after-free read in xfrm_alloc_spi+0x3b9/0xf30

Use-after-free read at 0xffff8881364c00c4 (in kfence-#95):
 xfrm_alloc_spi+0x3b9/0xf30
 xfrm_alloc_userspi+0x70b/0xc90
 xfrm_user_rcv_msg+0x7a3/0xab0
 netlink_rcv_skb+0x208/0x470
 xfrm_netlink_rcv+0x79/0x90
 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

kfence-#95: 0xffff8881364c0000-0xffff8881364c00ef, size=240, cache=skbuff_head_cache

allocated by task 27 on cpu 1 at 240.093968s (11.730085s ago):
 __alloc_skb+0x112/0x2d0
 rtmsg_ifinfo_build_skb+0x84/0x260
 rtmsg_ifinfo+0x8c/0x1a0
 netif_state_change+0x29e/0x3a0
 linkwatch_do_dev+0x117/0x170
 __linkwatch_run_queue+0x56a/0x7e0
 linkwatch_event+0x4c/0x60
 process_scheduled_works+0xae1/0x17b0
 worker_thread+0x8a0/0xda0
 kthread+0x711/0x8a0
 ret_from_fork+0x3fc/0x770
 ret_from_fork_asm+0x1a/0x30

freed by task 27 on cpu 1 at 240.094015s (11.759105s ago):
 netlink_broadcast_filtered+0x1188/0x12c0
 nlmsg_notify+0xf0/0x1a0
 netif_state_change+0x29e/0x3a0
 linkwatch_do_dev+0x117/0x170
 __linkwatch_run_queue+0x56a/0x7e0
 linkwatch_event+0x4c/0x60
 process_scheduled_works+0xae1/0x17b0
 worker_thread+0x8a0/0xda0
 kthread+0x711/0x8a0
 ret_from_fork+0x3fc/0x770
 ret_from_fork_asm+0x1a/0x30

CPU: 0 UID: 0 PID: 17747 Comm: syz.0.3497 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
RIP: 0010:xfrm_alloc_spi+0x3b9/0xf30
Code: c1 08 c1 74 0a e8 57 f9 9d f7 e9 14 02 00 00 49 8d 9d c4 00 00 00 48 89 d8 48 c1 e8 03 42 0f b6 04 20 84 c0 0f 85 9f 01 00 00 <8b> 1b 89 df 44 89 f6 e8 eb fa 9d f7 44 39 f3 0f 85 df 00 00 00 49
RSP: 0018:ffffc9000a7c70e0 EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffff8881364c00c4 RCX: 0000000000080000
RDX: ffffc900083ea000 RSI: 000000000000019d RDI: 000000000000019e
RBP: ffffc9000a7c7230 R08: 0000000000000000 R09: 0000000000000000
R10: dffffc0000000000 R11: fffff520014f8e0c R12: dffffc0000000000
R13: ffff8881364c0000 R14: 0000000060d6aa6a R15: ffffc9000a7c76a0
FS:  00007fdd4d7dc6c0(0000) GS:ffff8880b861b000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffff8881364c00c4 CR3: 000000003fe1a000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 xfrm_alloc_userspi+0x70b/0xc90
 xfrm_user_rcv_msg+0x7a3/0xab0
 netlink_rcv_skb+0x208/0x470
 xfrm_netlink_rcv+0x79/0x90
 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: 0033:0x7fdd4c98ebe9
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:00007fdd4d7dc038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007fdd4cbb5fa0 RCX: 00007fdd4c98ebe9
RDX: 0000000000000000 RSI: 0000200000001580 RDI: 0000000000000004
RBP: 00007fdd4ca11e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fdd4cbb6038 R14: 00007fdd4cbb5fa0 R15: 00007ffce7fd5838
 </TASK>
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