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BUG: KASAN: slab-out-of-bounds in bch2_dirent_init_name+0x396/0x8b0
Write of size 1985 at addr ffff8880236ab041 by task syz.5.86/6735

CPU: 0 UID: 0 PID: 6735 Comm: syz.5.86 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
 kasan_check_range+0x2b0/0x2c0
 __asan_memset+0x22/0x50
 bch2_dirent_init_name+0x396/0x8b0
 bch2_dirent_create_key+0x2a1/0x5f0
 bch2_dirent_create+0xc5/0xc80
 bch2_link_trans+0x39e/0x560
 __bch2_link+0x231/0x3f0
 bch2_symlink+0x183/0x240
 vfs_symlink+0x143/0x2f0
 do_symlinkat+0x1b1/0x3f0
 __x64_sys_symlink+0x7a/0x90
 do_syscall_64+0xfa/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f11b078ebe9
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:00007f11b1679038 EFLAGS: 00000246 ORIG_RAX: 0000000000000058
RAX: ffffffffffffffda RBX: 00007f11b09b5fa0 RCX: 00007f11b078ebe9
RDX: 0000000000000000 RSI: 00002000000059c0 RDI: 00002000000049c0
RBP: 00007f11b0811e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f11b09b6038 R14: 00007f11b09b5fa0 R15: 00007ffef4d2c298
 </TASK>

Allocated by task 6735:
 kasan_save_track+0x3e/0x80
 __kasan_kmalloc+0x93/0xb0
 __kmalloc_noprof+0x27a/0x4f0
 __bch2_trans_kmalloc+0x396/0x9d0
 bch2_dirent_create_key+0x113/0x5f0
 bch2_dirent_create+0xc5/0xc80
 bch2_link_trans+0x39e/0x560
 __bch2_link+0x231/0x3f0
 bch2_symlink+0x183/0x240
 vfs_symlink+0x143/0x2f0
 do_symlinkat+0x1b1/0x3f0
 __x64_sys_symlink+0x7a/0x90
 do_syscall_64+0xfa/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff8880236ab000
 which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 65 bytes inside of
 allocated 2048-byte region [ffff8880236ab000, ffff8880236ab800)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x236a8
head: order:3 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 ffff88801a442000 dead000000000100 dead000000000122
raw: 0000000000000000 0000000080080008 00000000f5000000 0000000000000000
head: 00fff00000000040 ffff88801a442000 dead000000000100 dead000000000122
head: 0000000000000000 0000000080080008 00000000f5000000 0000000000000000
head: 00fff00000000003 ffffea00008daa01 00000000ffffffff 00000000ffffffff
head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000008
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 5851, tgid 5851 (syz-executor), ts 67650995427, free_ts 67565998487
 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_node_track_caller_noprof+0x2f8/0x4e0
 kmalloc_reserve+0x136/0x290
 __alloc_skb+0x142/0x2d0
 rtmsg_ifinfo_build_skb+0x84/0x260
 rtmsg_ifinfo+0x8c/0x1a0
 register_netdevice+0x1712/0x1ae0
 __ip_tunnel_create+0x3e7/0x560
 ip_tunnel_init_net+0x2ba/0x800
 ops_init+0x35c/0x5c0
 setup_net+0x10c/0x320
page last free pid 5851 tgid 5851 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
 __kvmalloc_node_noprof+0x2b0/0x5f0
 proc_sys_call_handler+0x3ca/0x700
 vfs_write+0x5c9/0xb30
 ksys_write+0x145/0x250
 do_syscall_64+0xfa/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff8880236ab700: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8880236ab780: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff8880236ab800: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                   ^
 ffff8880236ab880: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8880236ab900: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
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