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BUG: KASAN: use-after-free in __xfrm_state_lookup+0x6ad/0x8d0
Read of size 2 at addr ffff88810e6da9c2 by task syz.0.8642/25573

CPU: 0 UID: 0 PID: 25573 Comm: syz.0.8642 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
 __xfrm_state_lookup+0x6ad/0x8d0
 xfrm_state_lookup+0x11e/0x1e0
 xfrm_user_state_lookup+0x231/0x370
 xfrm_del_sa+0xf1/0x3e0
 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: 0033:0x7fbe02d8ebe9
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:00007fbe03c33038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007fbe02fc5fa0 RCX: 00007fbe02d8ebe9
RDX: 0000000000000000 RSI: 0000200000000180 RDI: 0000000000000003
RBP: 00007fbe02e11e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fbe02fc6038 R14: 00007fbe02fc5fa0 R15: 00007ffd2538c288
 </TASK>

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff888111014080 pfn:0x10e6da
flags: 0x57ff00000000000(node=1|zone=2|lastcpupid=0x7ff)
page_type: f0(buddy)
raw: 057ff00000000000 ffffea0004c4fb88 ffffea0004d29688 0000000000000000
raw: ffff888111014080 0000000000000001 00000000f0000000 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as freed
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x2dc2(GFP_KERNEL|__GFP_HIGHMEM|__GFP_ZERO|__GFP_NOWARN), pid 25309, tgid 25309 (syz.1.8527), ts 408323785422, free_ts 409691327766
 post_alloc_hook+0x240/0x2a0
 get_page_from_freelist+0x21e4/0x22c0
 __alloc_frozen_pages_noprof+0x181/0x370
 alloc_pages_mpol+0x232/0x4a0
 alloc_pages_noprof+0xa9/0x190
 __vmalloc_node_range_noprof+0x97d/0x12f0
 __vmalloc_node_noprof+0xc2/0x110
 dup_task_struct+0x3e7/0x860
 copy_process+0x54b/0x3c00
 kernel_clone+0x21e/0x840
 __se_sys_clone3+0x256/0x2d0
 do_syscall_64+0xfa/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
page last free pid 792 tgid 792 stack trace:
 __free_frozen_pages+0xbc4/0xd30
 vfree+0x25a/0x400
 delayed_vfree_work+0x55/0x80
 process_scheduled_works+0xae1/0x17b0
 worker_thread+0x8a0/0xda0
 kthread+0x711/0x8a0
 ret_from_fork+0x3fc/0x770
 ret_from_fork_asm+0x1a/0x30

Memory state around the buggy address:
 ffff88810e6da880: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88810e6da900: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff88810e6da980: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                           ^
 ffff88810e6daa00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88810e6daa80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
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