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BUG: KASAN: use-after-free in ip_route_output_key_hash_rcu+0x1273/0x25d0
Read of size 8 at addr ffff88818de64000 by task syz.1.212/6793

CPU: 0 UID: 0 PID: 6793 Comm: syz.1.212 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+0xe8/0x150
 print_report+0xba/0x230
 kasan_report+0x117/0x150
 ip_route_output_key_hash_rcu+0x1273/0x25d0
 ip_route_output_key_hash+0x18d/0x2a0
 ip_route_output_flow+0x2a/0x150
 sctp_v4_get_dst+0x3f8/0x12b0
 sctp_transport_route+0x118/0x2f0
 sctp_assoc_add_peer+0x650/0x13b0
 sctp_connect_new_asoc+0x329/0x6b0
 sctp_sendmsg+0x1528/0x2c10
 ____sys_sendmsg+0x894/0xad0
 ___sys_sendmsg+0x2a5/0x360
 __x64_sys_sendmsg+0x1bd/0x2a0
 do_syscall_64+0x14d/0xf80
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fe9a239c799
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fe9a3334028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007fe9a2615fa0 RCX: 00007fe9a239c799
RDX: 0000000020008000 RSI: 0000200000000380 RDI: 000000000000000a
RBP: 00007fe9a2432bd9 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fe9a2616038 R14: 00007fe9a2615fa0 R15: 00007ffc0366adb8
 </TASK>

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x18de64
flags: 0x57ff00000000000(node=1|zone=2|lastcpupid=0x7ff)
raw: 057ff00000000000 dead000000000100 dead000000000122 0000000000000000
raw: 0000000000000000 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 0xcc0(GFP_KERNEL), pid 1, tgid 1 (swapper/0), ts 23022282818, free_ts 23617768952
 post_alloc_hook+0x231/0x280
 split_free_frozen_pages+0xd7/0x2f0
 alloc_contig_frozen_range_noprof+0x886/0xaa0
 alloc_contig_frozen_pages_noprof+0x642/0x7e0
 alloc_contig_pages_noprof+0x21/0xc0
 debug_vm_pgtable_alloc_huge_page+0x8a/0xd0
 init_args+0x8d0/0xbf0
 debug_vm_pgtable+0xf8/0x410
 do_one_initcall+0x250/0x8d0
 do_initcall_level+0x104/0x190
 do_initcalls+0x59/0xa0
 kernel_init_freeable+0x2a6/0x3e0
 kernel_init+0x1d/0x1d0
 ret_from_fork+0x51e/0xb90
 ret_from_fork_asm+0x1a/0x30
page last free pid 1 tgid 1 stack trace:
 __free_frozen_pages+0xc2b/0xdb0
 free_contig_range+0xbb/0x170
 destroy_args+0x4e5/0x570
 debug_vm_pgtable+0x3f8/0x410
 do_one_initcall+0x250/0x8d0
 do_initcall_level+0x104/0x190
 do_initcalls+0x59/0xa0
 kernel_init_freeable+0x2a6/0x3e0
 kernel_init+0x1d/0x1d0
 ret_from_fork+0x51e/0xb90
 ret_from_fork_asm+0x1a/0x30

Memory state around the buggy address:
 ffff88818de63f00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88818de63f80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff88818de64000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                   ^
 ffff88818de64080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88818de64100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
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