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BUG: KASAN: use-after-free in __kernfs_remove+0x9dd/0xb30
Read of size 2 at addr ffff888042f6b350 by task syz-executor.2/33585

CPU: 0 PID: 33585 Comm: syz-executor.2 Not tainted 6.0.0-rc2-next-20220826 #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-0-g155821a1990b-prebuilt.qemu.org 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0x8b/0xb3
 print_report.cold+0x5e/0x5e5
 kasan_report+0xb1/0x1c0
 __kernfs_remove+0x9dd/0xb30
 kernfs_remove_by_name_ns+0xa8/0x110
 sysfs_slab_add+0x142/0x1f0
 __kmem_cache_create+0x49d/0x600
 kmem_cache_create_usercopy+0x1fd/0x2e0
 p9_client_create+0xc85/0x1050
 v9fs_session_init+0x1dd/0x1670
 v9fs_mount+0xb9/0xbd0
 legacy_get_tree+0x105/0x220
 vfs_get_tree+0x8e/0x300
 path_mount+0x1310/0x1e20
 __x64_sys_mount+0x282/0x300
 do_syscall_64+0x3b/0x90
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7ff7659dcb19
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 bc ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ff762f52188 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007ff765aeff60 RCX: 00007ff7659dcb19
RDX: 0000000020000040 RSI: 0000000020000000 RDI: 0000000000000000
RBP: 00007ff765a36f6d R08: 0000000020000400 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fff3fb11edf R14: 00007ff762f52300 R15: 0000000000022000
 </TASK>

Allocated by task 33548:
 kasan_save_stack+0x1e/0x40
 __kasan_slab_alloc+0x66/0x80
 kmem_cache_alloc+0x1b1/0x3e0
 __kernfs_new_node+0xd4/0x8c0
 kernfs_create_dir_ns+0x9c/0x230
 sysfs_create_dir_ns+0x127/0x290
 kobject_add_internal+0x24c/0x8e0
 kobject_init_and_add+0x101/0x160
 sysfs_slab_add+0x165/0x1f0
 __kmem_cache_create+0x49d/0x600
 kmem_cache_create_usercopy+0x1fd/0x2e0
 p9_client_create+0xc85/0x1050
 v9fs_session_init+0x1dd/0x1670
 v9fs_mount+0xb9/0xbd0
 legacy_get_tree+0x105/0x220
 vfs_get_tree+0x8e/0x300
 path_mount+0x1310/0x1e20
 __x64_sys_mount+0x282/0x300
 do_syscall_64+0x3b/0x90
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

Freed by task 33585:
 kasan_save_stack+0x1e/0x40
 kasan_set_track+0x21/0x30
 kasan_set_free_info+0x20/0x40
 __kasan_slab_free+0x108/0x190
 kmem_cache_free+0xf7/0x610
 kernfs_put.part.0+0x2c7/0x540
 kernfs_put+0x42/0x50
 __kernfs_remove+0x7d4/0xb30
 kernfs_remove_by_name_ns+0xa8/0x110
 sysfs_slab_add+0x142/0x1f0
 __kmem_cache_create+0x49d/0x600
 kmem_cache_create_usercopy+0x1fd/0x2e0
 p9_client_create+0xc85/0x1050
 v9fs_session_init+0x1dd/0x1670
 v9fs_mount+0xb9/0xbd0
 legacy_get_tree+0x105/0x220
 vfs_get_tree+0x8e/0x300
 path_mount+0x1310/0x1e20
 __x64_sys_mount+0x282/0x300
 do_syscall_64+0x3b/0x90
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

The buggy address belongs to the object at ffff888042f6b2b8
 which belongs to the cache kernfs_node_cache of size 168
The buggy address is located 152 bytes inside of
 168-byte region [ffff888042f6b2b8, ffff888042f6b360)

The buggy address belongs to the physical page:
page:000000001656af94 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x42f6b
flags: 0x100000000000200(slab|node=0|zone=1)
raw: 0100000000000200 0000000000000000 dead000000000122 ffff88800847b8c0
raw: 0000000000000000 0000000000110011 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff888042f6b200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fc
 ffff888042f6b280: fc fc fc fc fc fc fc fa fb fb fb fb fb fb fb fb
>ffff888042f6b300: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
                                                 ^
 ffff888042f6b380: fc fc fc fc fa fb fb fb fb fb fb fb fb fb fb fb
 ffff888042f6b400: fb fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc
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9pnet_virtio: no channels available for device 127.0.0.1