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

Use-after-free read at 0xffff8881365e4cc4 (in kfence-#241):
 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-#241: 0xffff8881365e4000-0xffff8881365e4017, size=24, cache=kmalloc-32

allocated by task 1027 on cpu 0 at 781.356479s (0.916394s ago):
 kmem_cache_free+0x166/0x400
 task_work_run+0x1d4/0x260
 exit_to_user_mode_loop+0xec/0x110
 do_syscall_64+0x2bd/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

freed by task 1067 on cpu 0 at 781.388606s (0.896565s ago):
 slab_free_after_rcu_debug+0x60/0x2a0
 rcu_core+0xcab/0x1770
 handle_softirqs+0x286/0x870
 do_softirq+0xec/0x180
 __local_bh_enable_ip+0x17d/0x1c0
 fpu_clone+0x53f/0xbb0
 copy_thread+0x3f5/0x9a0
 copy_process+0x18ae/0x3c00
 kernel_clone+0x21e/0x840
 __se_sys_clone3+0x256/0x2d0
 do_syscall_64+0xfa/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

CPU: 0 UID: 0 PID: 1138 Comm: syz.4.7121 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 67 28 9c 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 fb 29 9c f7 44 39 f3 0f 85 df 00 00 00 49
RSP: 0018:ffffc90008faf0e0 EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffff8881365e4cc4 RCX: 0000000000080000
RDX: ffffc9002932a000 RSI: 000000000000023f RDI: 0000000000000240
RBP: ffffc90008faf230 R08: 0000000000000000 R09: ffffffff8a238430
R10: dffffc0000000000 R11: fffff520011f5e0c R12: dffffc0000000000
R13: ffff8881365e4c00 R14: 00000000de5a0000 R15: ffffc90008faf6a0
FS:  00007f449933d6c0(0000) GS:ffff8880b8613000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffff8881365e4cc4 CR3: 0000000130cee000 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: 0033:0x7f449858ec29
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:00007f449933d038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f44987d5fa0 RCX: 00007f449858ec29
RDX: 0000000000000000 RSI: 0000200000000280 RDI: 0000000000000009
RBP: 00007f4498611e41 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f44987d6038 R14: 00007f44987d5fa0 R15: 00007ffe90cc2338
 </TASK>
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