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BUG: KASAN: use-after-free in kobject_put+0x220/0x270 lib/kobject.c:748
Read of size 1 at addr ffff888098fe283c by task syz-executor476/6953

CPU: 0 PID: 6953 Comm: syz-executor476 Not tainted 5.9.0-rc2-next-20200828-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x18f/0x20d lib/dump_stack.c:118
 print_address_description.constprop.0.cold+0xae/0x497 mm/kasan/report.c:383
 __kasan_report mm/kasan/report.c:513 [inline]
 kasan_report.cold+0x1f/0x37 mm/kasan/report.c:530
 kobject_put+0x220/0x270 lib/kobject.c:748
 delete_partition+0x134/0x220 block/partitions/core.c:324
 bdev_del_partition+0x18b/0x1d0 block/partitions/core.c:549
 blkpg_do_ioctl+0x2d6/0x330 block/ioctl.c:33
 blkpg_ioctl block/ioctl.c:69 [inline]
 blkdev_ioctl+0x58a/0x700 block/ioctl.c:589
 block_ioctl+0xf9/0x140 fs/block_dev.c:1871
 vfs_ioctl fs/ioctl.c:48 [inline]
 __do_sys_ioctl fs/ioctl.c:753 [inline]
 __se_sys_ioctl fs/ioctl.c:739 [inline]
 __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:739
 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x446959
Code: e8 0c e8 ff ff 48 83 c4 18 c3 0f 1f 80 00 00 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 0f 83 db 06 fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007ff78aa55d98 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00000000006dbc38 RCX: 0000000000446959
RDX: 0000000020000000 RSI: 0000000000001269 RDI: 0000000000000005
RBP: 00000000006dbc30 R08: 00007ff78aa56700 R09: 0000000000000000
R10: 00007ff78aa56700 R11: 0000000000000246 R12: 00000000006dbc3c
R13: 00000000000000a9 R14: 00b747111e42e3ec R15: 02ba2b7a04b8ac00

Allocated by task 6941:
 kasan_save_stack+0x1b/0x40 mm/kasan/common.c:48
 kasan_set_track mm/kasan/common.c:56 [inline]
 __kasan_kmalloc.constprop.0+0xbf/0xd0 mm/kasan/common.c:461
 kmem_cache_alloc_trace+0x16e/0x2c0 mm/slab.c:3550
 kmalloc include/linux/slab.h:554 [inline]
 kzalloc include/linux/slab.h:666 [inline]
 kobject_create lib/kobject.c:783 [inline]
 kobject_create_and_add+0x42/0xb0 lib/kobject.c:809
 add_partition+0x989/0xd80 block/partitions/core.c:443
 bdev_add_partition+0xb6/0x130 block/partitions/core.c:518
 blkpg_do_ioctl+0x2be/0x330 block/ioctl.c:52
 blkpg_ioctl block/ioctl.c:69 [inline]
 blkdev_ioctl+0x58a/0x700 block/ioctl.c:589
 block_ioctl+0xf9/0x140 fs/block_dev.c:1871
 vfs_ioctl fs/ioctl.c:48 [inline]
 __do_sys_ioctl fs/ioctl.c:753 [inline]
 __se_sys_ioctl fs/ioctl.c:739 [inline]
 __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:739
 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Freed by task 6952:
 kasan_save_stack+0x1b/0x40 mm/kasan/common.c:48
 kasan_set_track+0x1c/0x30 mm/kasan/common.c:56
 kasan_set_free_info+0x1b/0x30 mm/kasan/generic.c:355
 __kasan_slab_free+0xd8/0x120 mm/kasan/common.c:422
 __cache_free mm/slab.c:3418 [inline]
 kfree+0x103/0x2c0 mm/slab.c:3756
 kobject_cleanup lib/kobject.c:704 [inline]
 kobject_release lib/kobject.c:735 [inline]
 kref_put include/linux/kref.h:65 [inline]
 kobject_put+0x171/0x270 lib/kobject.c:752
 delete_partition+0x134/0x220 block/partitions/core.c:324
 bdev_del_partition+0x18b/0x1d0 block/partitions/core.c:549
 blkpg_do_ioctl+0x2d6/0x330 block/ioctl.c:33
 blkpg_ioctl block/ioctl.c:69 [inline]
 blkdev_ioctl+0x58a/0x700 block/ioctl.c:589
 block_ioctl+0xf9/0x140 fs/block_dev.c:1871
 vfs_ioctl fs/ioctl.c:48 [inline]
 __do_sys_ioctl fs/ioctl.c:753 [inline]
 __se_sys_ioctl fs/ioctl.c:739 [inline]
 __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:739
 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

The buggy address belongs to the object at ffff888098fe2800
 which belongs to the cache kmalloc-64 of size 64
The buggy address is located 60 bytes inside of
 64-byte region [ffff888098fe2800, ffff888098fe2840)
The buggy address belongs to the page:
page:0000000054665c2f refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x98fe2
flags: 0xfffe0000000200(slab)
raw: 00fffe0000000200 ffffea0002a4af08 ffffea000298e688 ffff8880aa040200
raw: 0000000000000000 ffff888098fe2000 0000000100000020 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff888098fe2700: 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc
 ffff888098fe2780: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
>ffff888098fe2800: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
                                        ^
 ffff888098fe2880: 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc
 ffff888098fe2900: 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc
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