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BUG: KASAN: use-after-free in __xfrm_state_lookup+0x6ad/0x8d0
Read of size 2 at addr ffff88803a368a42 by task syz.1.7019/26248

CPU: 0 UID: 0 PID: 26248 Comm: syz.1.7019 Not tainted 6.16.0-syzkaller-11895-gcca7a0aae895 #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
 ipcomp4_init_state+0x205/0xb20
 __xfrm_init_state+0xa76/0x13f0
 xfrm_add_sa+0x2f5b/0x4070
 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: 0033:0x7f31cf18ebe9
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:00007f31cff6d038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f31cf3b5fa0 RCX: 00007f31cf18ebe9
RDX: 0000000000000000 RSI: 00002000000035c0 RDI: 0000000000000003
RBP: 00007f31cf211e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f31cf3b6038 R14: 00007f31cf3b5fa0 R15: 00007ffd542cdec8
 </TASK>

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff88803a369200 pfn:0x3a368
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
page_type: f0(buddy)
raw: 00fff00000000000 ffffea000109be08 ffffea0000fe7c08 0000000000000000
raw: ffff88803a369200 0000000000000002 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 0x2cc2(GFP_KERNEL|__GFP_HIGHMEM|__GFP_NOWARN), pid 19998, tgid 19997 (syz.2.5002), ts 518901967944, free_ts 519007079045
 post_alloc_hook+0x240/0x2a0
 get_page_from_freelist+0x21e4/0x22c0
 __alloc_frozen_pages_noprof+0x181/0x370
 __alloc_pages_noprof+0xa/0x30
 pcpu_populate_chunk+0x182/0xb30
 pcpu_alloc_noprof+0xcbf/0x16b0
 bpf_map_alloc_percpu+0xbc/0x1b0
 prealloc_init+0x225/0x630
 htab_map_alloc+0x6ce/0xc70
 map_create+0xaa3/0x14d0
 __sys_bpf+0x60f/0x870
 __x64_sys_bpf+0x7c/0x90
 do_syscall_64+0xfa/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
page last free pid 12815 tgid 12815 stack trace:
 __free_frozen_pages+0xbc4/0xd30
 pcpu_depopulate_chunk+0x45f/0x500
 pcpu_balance_workfn+0x350/0xe00
 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:
 ffff88803a368900: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88803a368980: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff88803a368a00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                           ^
 ffff88803a368a80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88803a368b00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
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