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BUG: KASAN: use-after-free in xfrm_alloc_spi+0x570/0xf30
Read of size 4 at addr ffff88811158e944 by task syz.1.2006/13741

CPU: 0 UID: 0 PID: 13741 Comm: syz.1.2006 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
 pfkey_getspi+0x7a8/0xee0
 pfkey_sendmsg+0xbfe/0x1090
 __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: 0033:0x7f0ec698ebe9
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:00007f0ec7896038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f0ec6bb5fa0 RCX: 00007f0ec698ebe9
RDX: 0000000020000000 RSI: 0000200000000040 RDI: 0000000000000004
RBP: 00007f0ec6a11e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f0ec6bb6038 R14: 00007f0ec6bb5fa0 R15: 00007ffc3409ff68
 </TASK>

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff8881068f6b80 pfn:0x11158e
flags: 0x57ff00000000000(node=1|zone=2|lastcpupid=0x7ff)
raw: 057ff00000000000 0000000000000000 ffffea0004456390 0000000000000000
raw: ffff8881068f6b80 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 2, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 13742, tgid 13740 (syz.2.2007), ts 177204945946, free_ts 166673710244
 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/0x1410
 __kmalloc_noprof+0x305/0x4f0
 copy_splice_read+0x143/0xa50
 splice_direct_to_actor+0x4d0/0xcc0
 do_splice_direct+0x181/0x270
 do_sendfile+0x4da/0x7e0
 __se_sys_sendfile64+0x13e/0x190
 do_syscall_64+0xfa/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
page last free pid 5690 tgid 5690 stack trace:
 __free_frozen_pages+0xbc4/0xd30
 __put_partials+0x156/0x1a0
 put_cpu_partial+0x17c/0x250
 __slab_free+0x2d5/0x3c0
 qlist_free_all+0x97/0x140
 kasan_quarantine_reduce+0x148/0x160
 __kasan_slab_alloc+0x22/0x80
 kmem_cache_alloc_node_noprof+0x1bb/0x3c0
 __alloc_skb+0x112/0x2d0
 inet6_netconf_notify_devconf+0x10f/0x1d0
 addrconf_exit_net+0xcf/0x2c0
 ops_undo_list+0x49a/0x990
 cleanup_net+0x4c5/0x800
 process_scheduled_works+0xae1/0x17b0
 worker_thread+0x8a0/0xda0
 kthread+0x711/0x8a0

Memory state around the buggy address:
 ffff88811158e800: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88811158e880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88811158e900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                           ^
 ffff88811158e980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88811158ea00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
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