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BUG: KASAN: slab-use-after-free in __xfrm_state_lookup+0x6ad/0x8d0
Read of size 2 at addr ffff888020218142 by task syz.4.3425/15489

CPU: 0 UID: 0 PID: 15489 Comm: syz.4.3425 Not tainted 6.17.0-rc1-syzkaller-00036-gdfc0f6373094-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_state_lookup+0x6ad/0x8d0
 xfrm_state_lookup+0x11e/0x1e0
 vti6_err+0x2f7/0x520
 xfrm6_ipcomp_err+0xc1/0x210
 icmpv6_notify+0x391/0x7e0
 ndisc_redirect_rcv+0x45e/0x850
 icmpv6_rcv+0x139a/0x1c80
 ip6_protocol_deliver_rcu+0xe0b/0x15c0
 ip6_input_finish+0x191/0x370
 NF_HOOK+0x30c/0x3a0
 ip6_input+0x16a/0x270
 ip6_mc_input+0x5c8/0xaf0
 NF_HOOK+0x30c/0x3a0
 __netif_receive_skb+0xd3/0x380
 netif_receive_skb+0x1cb/0x790
 tun_rx_batched+0x1b9/0x730
 tun_get_user+0x2aa2/0x3e20
 tun_chr_write_iter+0x113/0x200
 vfs_write+0x5c9/0xb30
 ksys_write+0x145/0x250
 do_syscall_64+0xfa/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7ff5c9b8d69f
Code: 89 54 24 18 48 89 74 24 10 89 7c 24 08 e8 f9 92 02 00 48 8b 54 24 18 48 8b 74 24 10 41 89 c0 8b 7c 24 08 b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 31 44 89 c7 48 89 44 24 08 e8 4c 93 02 00 48
RSP: 002b:00007ff5caa9a000 EFLAGS: 00000293 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007ff5c9db5fa0 RCX: 00007ff5c9b8d69f
RDX: 000000000000013e RSI: 0000200000000680 RDI: 00000000000000c8
RBP: 00007ff5c9c11e19 R08: 0000000000000000 R09: 0000000000000000
R10: 000000000000013e R11: 0000000000000293 R12: 0000000000000000
R13: 00007ff5c9db6038 R14: 00007ff5c9db5fa0 R15: 00007ffcc38c02e8
 </TASK>

Allocated by task 9850:
 kasan_save_track+0x3e/0x80
 __kasan_slab_alloc+0x6c/0x80
 kmem_cache_alloc_noprof+0x1c1/0x3c0
 xfrm_state_alloc+0x24/0x2f0
 __find_acq_core+0x8a7/0x1c00
 xfrm_find_acq+0x78/0xa0
 xfrm_alloc_userspi+0x6b3/0xc90
 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

Freed by task 6281:
 kasan_save_track+0x3e/0x80
 kasan_save_free_info+0x46/0x50
 __kasan_slab_free+0x5b/0x80
 kmem_cache_free+0x18f/0x400
 xfrm_state_gc_task+0x52d/0x6b0
 process_scheduled_works+0xae1/0x17b0
 worker_thread+0x8a0/0xda0
 kthread+0x711/0x8a0
 ret_from_fork+0x3fc/0x770
 ret_from_fork_asm+0x1a/0x30

The buggy address belongs to the object at ffff888020218000
 which belongs to the cache xfrm_state of size 928
The buggy address is located 322 bytes inside of
 freed 928-byte region [ffff888020218000, ffff8880202183a0)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff888020218900 pfn:0x20218
head: order:2 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0xfff00000000040(head|node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000040 ffff88801e3583c0 dead000000000122 0000000000000000
raw: ffff888020218900 00000000800e000d 00000000f5000000 0000000000000000
head: 00fff00000000040 ffff88801e3583c0 dead000000000122 0000000000000000
head: ffff888020218900 00000000800e000d 00000000f5000000 0000000000000000
head: 00fff00000000002 ffffea0000808601 00000000ffffffff 00000000ffffffff
head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000004
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 2, migratetype Unmovable, gfp_mask 0x52820(GFP_ATOMIC|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP), pid 6309, tgid 6308 (syz.1.135), ts 70875162470, free_ts 70870942584
 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
 kmem_cache_alloc_noprof+0x283/0x3c0
 xfrm_state_alloc+0x24/0x2f0
 pfkey_add+0x6e4/0x2e00
 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
page last free pid 6308 tgid 6308 stack trace:
 __free_frozen_pages+0xbc4/0xd30
 stack_depot_save_flags+0x436/0x860
 kasan_save_track+0x4f/0x80
 __kasan_slab_alloc+0x6c/0x80
 kmem_cache_alloc_noprof+0x1c1/0x3c0
 start_this_handle+0x37c/0x21c0
 jbd2__journal_start+0x2c1/0x5b0
 __ext4_journal_start_sb+0x227/0x5c0
 ext4_dirty_inode+0x93/0x110
 __mark_inode_dirty+0x2d1/0xdf0
 touch_atime+0x59b/0x6d0
 ext4_file_mmap_prepare+0x24d/0x440
 mmap_region+0xb41/0x20c0
 do_mmap+0xc45/0x10d0
 vm_mmap_pgoff+0x2a6/0x4d0
 ksys_mmap_pgoff+0x51f/0x760

Memory state around the buggy address:
 ffff888020218000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888020218080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888020218100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                           ^
 ffff888020218180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888020218200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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