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

Use-after-free read at 0xffff888136528cc4 (in kfence-#147):
 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-#147: 0xffff888136528000-0xffff888136528fff, size=4096, cache=names_cache

allocated by task 5852 on cpu 0 at 230.125209s (0.516026s ago):
 getname_flags+0xb8/0x540
 user_path_at+0x24/0x60
 __x64_sys_umount+0xee/0x160
 do_syscall_64+0xfa/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

freed by task 5852 on cpu 0 at 230.125220s (0.530536s ago):
 user_path_at+0x44/0x60
 __x64_sys_umount+0xee/0x160
 do_syscall_64+0xfa/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

CPU: 0 UID: 0 PID: 15261 Comm: syz.2.2758 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 3d 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 3e 9d f7 44 39 f3 0f 85 df 00 00 00 49
RSP: 0018:ffffc900074370e0 EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffff888136528cc4 RCX: 0000000000080000
RDX: ffffc9000887b000 RSI: 0000000000000234 RDI: 0000000000000235
RBP: ffffc90007437230 R08: 0000000000000000 R09: ffffffff8a227000
R10: dffffc0000000000 R11: fffff52000e86e0c R12: dffffc0000000000
R13: ffff888136528c00 R14: 00000000f7020000 R15: ffffc900074376a0
FS:  00007f4754ff66c0(0000) GS:ffff8880b8614000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffff888136528cc4 CR3: 0000000039ddc000 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: 0033:0x7f4756d8eba9
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:00007f4754ff6038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f4756fd5fa0 RCX: 00007f4756d8eba9
RDX: 0000000024000014 RSI: 0000200000000200 RDI: 0000000000000003
RBP: 00007f4756e11e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f4756fd6038 R14: 00007f4756fd5fa0 R15: 00007ffc83a7cc38
 </TASK>
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