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BUG: KASAN: use-after-free in xfrm_alloc_spi+0x570/0xf30
Read of size 4 at addr ffff888021c38e44 by task syz.0.5068/17607

CPU: 0 UID: 0 PID: 17607 Comm: syz.0.5068 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_alloc_spi+0x570/0xf30
 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
RIP: 0033:0x7fe4acb8eba9
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:00007fe4adae7038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007fe4acdd5fa0 RCX: 00007fe4acb8eba9
RDX: 0000000000000000 RSI: 00002000000004c0 RDI: 0000000000000003
RBP: 00007fe4acc11e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fe4acdd6038 R14: 00007fe4acdd5fa0 R15: 00007ffda8c275c8
 </TASK>

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff888021c3bc00 pfn:0x21c38
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
page_type: f0(buddy)
raw: 00fff00000000000 ffffea0000f90408 ffffea0000896708 0000000000000000
raw: ffff888021c3bc00 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 0x6cc0(GFP_KERNEL|__GFP_NOWARN|__GFP_RETRY_MAYFAIL), pid 17183, tgid 17182 (syz.2.4888), ts 264359794923, free_ts 265483037109
 post_alloc_hook+0x240/0x2a0
 get_page_from_freelist+0x21e4/0x22c0
 __alloc_frozen_pages_noprof+0x181/0x370
 alloc_pages_bulk_noprof+0x560/0x710
 kasan_populate_vmalloc+0xd1/0x270
 alloc_vmap_area+0xd62/0x14a0
 __get_vm_area_node+0x1f8/0x300
 __vmalloc_node_range_noprof+0x301/0x12f0
 bpf_map_area_alloc+0x12d/0x180
 bloom_map_alloc+0x22f/0x470
 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 5881 tgid 5881 stack trace:
 __free_frozen_pages+0xbc4/0xd30
 kasan_depopulate_vmalloc_pte+0x6d/0x90
 __apply_to_page_range+0xb66/0x13d0
 kasan_release_vmalloc+0xa2/0xd0
 purge_vmap_node+0x214/0x8f0
 process_scheduled_works+0xae1/0x17b0
 worker_thread+0x8a0/0xda0
 kthread+0x711/0x8a0
 ret_from_fork+0x439/0x7d0
 ret_from_fork_asm+0x1a/0x30

Memory state around the buggy address:
 ffff888021c38d00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888021c38d80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff888021c38e00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                           ^
 ffff888021c38e80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888021c38f00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
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