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BUG: KASAN: use-after-free in __xfrm_state_lookup+0x6ad/0x8d0
Read of size 2 at addr ffff888027e28142 by task syz.1.1281/9009

CPU: 1 UID: 0 PID: 9009 Comm: syz.1.1281 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
 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: 0033:0x7f855b78ebe9
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:00007f855c68b038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f855b9c5fa0 RCX: 00007f855b78ebe9
RDX: 0000000000000000 RSI: 0000200000000040 RDI: 0000000000000004
RBP: 00007f855b811e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f855b9c6038 R14: 00007f855b9c5fa0 R15: 00007ffc761099e8
 </TASK>

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff888027e2bb80 pfn:0x27e28
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
page_type: f0(buddy)
raw: 00fff00000000000 ffffea0000d08308 ffffea0000f4ab08 0000000000000000
raw: ffff888027e2bb80 0000000000000002 00000000f0000000 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as freed
page last allocated via order 2, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 8620, tgid 8619 (syz.0.1114), ts 115911393035, free_ts 119461471350
 post_alloc_hook+0x240/0x2a0
 get_page_from_freelist+0x21e4/0x22c0
 __alloc_frozen_pages_noprof+0x181/0x370
 alloc_pages_mpol+0x232/0x4a0
 allocate_slab+0x8a/0x370
 ___slab_alloc+0xbeb/0x1420
 kmem_cache_alloc_node_noprof+0x280/0x3c0
 kmalloc_reserve+0xbd/0x290
 __alloc_skb+0x142/0x2d0
 netlink_ack+0x146/0xa50
 netlink_rcv_skb+0x28c/0x470
 netlink_unicast+0x82f/0x9e0
 netlink_sendmsg+0x805/0xb30
 __sock_sendmsg+0x21c/0x270
 ____sys_sendmsg+0x505/0x830
 ___sys_sendmsg+0x21f/0x2a0
page last free pid 5854 tgid 5854 stack trace:
 __free_frozen_pages+0xbc4/0xd30
 __slab_free+0x303/0x3c0
 qlist_free_all+0x97/0x140
 kasan_quarantine_reduce+0x148/0x160
 __kasan_slab_alloc+0x22/0x80
 __kmalloc_noprof+0x224/0x4f0
 tomoyo_realpath_from_path+0xe3/0x5d0
 tomoyo_path_number_perm+0x1e8/0x5a0
 security_file_ioctl+0xcb/0x2d0
 __se_sys_ioctl+0x47/0x170
 do_syscall_64+0xfa/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff888027e28000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888027e28080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff888027e28100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                           ^
 ffff888027e28180: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888027e28200: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
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