==================================================================
BUG: KASAN: use-after-free in xfrm_alloc_spi+0x570/0xf30
Read of size 4 at addr ffff88803f8764c4 by task syz.0.6354/20499

CPU: 1 UID: 0 PID: 20499 Comm: syz.0.6354 Not tainted 6.16.0-syzkaller-06600-g1dbf1d590d10-dirty #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: 0033:0x7f247ef8ebe9
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:00007f247feb9038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f247f1b5fa0 RCX: 00007f247ef8ebe9
RDX: 000000000400c014 RSI: 0000200000000340 RDI: 0000000000000003
RBP: 00007f247f011e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f247f1b6038 R14: 00007f247f1b5fa0 R15: 00007fff85cde648
 </TASK>

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff88803f876f00 pfn:0x3f876
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000000 dead000000000100 dead000000000122 0000000000000000
raw: ffff88803f876f00 0000000000000000 00000000ffffffff 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 0x52820(GFP_ATOMIC|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP), pid 19389, tgid 19388 (syz.2.5871), ts 224559488960, free_ts 227456519341
 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/0x3b0
 ___slab_alloc+0xbfc/0x1480
 kmem_cache_alloc_noprof+0x283/0x3c0
 dst_alloc+0x105/0x170
 ip_route_input_rcu+0x1ed5/0x2ff0
 ip_route_input_noref+0x167/0x250
 ip_rcv_finish_core+0x5af/0x1c00
 ip_sublist_rcv+0x397/0x9b0
 ip_list_rcv+0x3e2/0x430
 __netif_receive_skb_list_core+0x7d2/0x800
 netif_receive_skb_list_internal+0x975/0xcc0
 netif_receive_skb_list+0x54/0x450
page last free pid 5763 tgid 5763 stack trace:
 __free_frozen_pages+0xc71/0xe70
 __put_partials+0x161/0x1c0
 put_cpu_partial+0x17c/0x250
 __slab_free+0x2f7/0x400
 qlist_free_all+0x97/0x140
 kasan_quarantine_reduce+0x148/0x160
 __kasan_slab_alloc+0x22/0x80
 kmem_cache_alloc_noprof+0x1c1/0x3c0
 jbd2__journal_start+0x146/0x5b0
 __ext4_journal_start_sb+0x227/0x5c0
 ext4_dirty_inode+0x93/0x110
 __mark_inode_dirty+0x2d1/0xdf0
 file_update_time+0x40c/0x490
 ext4_page_mkwrite+0x1fa/0x1110
 do_page_mkwrite+0x14d/0x310
 do_wp_page+0x268d/0x5800

Memory state around the buggy address:
 ffff88803f876380: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88803f876400: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff88803f876480: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                           ^
 ffff88803f876500: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88803f876580: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================
