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BUG: KASAN: use-after-free in bdev_nr_sectors include/linux/genhd.h:266 [inline]
BUG: KASAN: use-after-free in disk_part_iter_next+0x49d/0x530 block/genhd.c:206
Read of size 8 at addr ffff8880199a50a8 by task syz-executor.4/10436

CPU: 0 PID: 10436 Comm: syz-executor.4 Not tainted 5.12.0-rc4-next-20210326-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:79 [inline]
 dump_stack+0x141/0x1d7 lib/dump_stack.c:120
 print_address_description.constprop.0.cold+0x5b/0x2f8 mm/kasan/report.c:232
 __kasan_report mm/kasan/report.c:399 [inline]
 kasan_report.cold+0x7c/0xd8 mm/kasan/report.c:416
 bdev_nr_sectors include/linux/genhd.h:266 [inline]
 disk_part_iter_next+0x49d/0x530 block/genhd.c:206
 blk_drop_partitions+0x10a/0x180 block/partitions/core.c:541
 bdev_disk_changed+0x211/0x3c0 fs/block_dev.c:1244
 __loop_clr_fd+0x7c7/0xff0 drivers/block/loop.c:1272
 lo_release+0x1ac/0x1f0 drivers/block/loop.c:1924
 __blkdev_put+0x5d4/0x790 fs/block_dev.c:1588
 blkdev_put+0x92/0x580 fs/block_dev.c:1641
 blkdev_close+0x8c/0xb0 fs/block_dev.c:1649
 __fput+0x288/0x920 fs/file_table.c:280
 task_work_run+0xdd/0x1a0 kernel/task_work.c:143
 get_signal+0x1c89/0x2100 kernel/signal.c:2558
 arch_do_signal_or_restart+0x2a8/0x1eb0 arch/x86/kernel/signal.c:789
 handle_signal_work kernel/entry/common.c:147 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:171 [inline]
 exit_to_user_mode_prepare+0x148/0x250 kernel/entry/common.c:208
 __syscall_exit_to_user_mode_work kernel/entry/common.c:290 [inline]
 syscall_exit_to_user_mode+0x19/0x60 kernel/entry/common.c:301
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x466459
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:00007f5997813188 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: 0000000000000000 RBX: 000000000056c008 RCX: 0000000000466459
RDX: 0000000020000080 RSI: 0000000000004c02 RDI: 0000000000000003
RBP: 00000000004bf9fb R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056c008
R13: 00007ffd199db02f R14: 00007f5997813300 R15: 0000000000022000

Allocated by task 8338:
 kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38
 kasan_set_track mm/kasan/common.c:46 [inline]
 set_alloc_info mm/kasan/common.c:428 [inline]
 __kasan_slab_alloc+0x84/0xa0 mm/kasan/common.c:461
 kasan_slab_alloc include/linux/kasan.h:236 [inline]
 slab_post_alloc_hook mm/slab.h:525 [inline]
 slab_alloc_node mm/slub.c:2909 [inline]
 slab_alloc mm/slub.c:2917 [inline]
 kmem_cache_alloc+0x212/0x390 mm/slub.c:2922
 bdev_alloc_inode+0x18/0x80 fs/block_dev.c:795
 alloc_inode+0x61/0x230 fs/inode.c:234
 new_inode_pseudo fs/inode.c:928 [inline]
 new_inode+0x27/0x2f0 fs/inode.c:957
 bdev_alloc+0x20/0x2f0 fs/block_dev.c:885
 add_partition+0x1ab/0x880 block/partitions/core.c:346
 bdev_add_partition+0xb6/0x130 block/partitions/core.c:449
 blkpg_do_ioctl+0x2d0/0x340 block/ioctl.c:43
 blkpg_ioctl block/ioctl.c:60 [inline]
 blkdev_ioctl+0x577/0x6d0 block/ioctl.c:548
 block_ioctl+0xf9/0x140 fs/block_dev.c:1667
 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+0x44/0xae

Freed by task 10435:
 kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38
 kasan_set_track+0x1c/0x30 mm/kasan/common.c:46
 kasan_set_free_info+0x20/0x30 mm/kasan/generic.c:357
 ____kasan_slab_free mm/kasan/common.c:360 [inline]
 ____kasan_slab_free mm/kasan/common.c:325 [inline]
 __kasan_slab_free+0xfb/0x130 mm/kasan/common.c:368
 kasan_slab_free include/linux/kasan.h:212 [inline]
 slab_free_hook mm/slub.c:1578 [inline]
 slab_free_freelist_hook+0xdf/0x240 mm/slub.c:1603
 slab_free mm/slub.c:3163 [inline]
 kmem_cache_free+0x8a/0x730 mm/slub.c:3179
 i_callback+0x3f/0x70 fs/inode.c:223
 rcu_do_batch kernel/rcu/tree.c:2559 [inline]
 rcu_core+0x7ab/0x13b0 kernel/rcu/tree.c:2794
 __do_softirq+0x29b/0x9f6 kernel/softirq.c:559

Last potentially related work creation:
 kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38
 kasan_record_aux_stack+0xe5/0x110 mm/kasan/generic.c:345
 __call_rcu kernel/rcu/tree.c:3039 [inline]
 call_rcu+0xb1/0x750 kernel/rcu/tree.c:3114
 destroy_inode+0x129/0x1b0 fs/inode.c:289
 iput_final fs/inode.c:1654 [inline]
 iput.part.0+0x57e/0x810 fs/inode.c:1680
 iput+0x58/0x70 fs/inode.c:1670
 disk_part_iter_exit block/genhd.c:235 [inline]
 disk_part_iter_next+0x9a/0x530 block/genhd.c:202
 blk_drop_partitions+0x10a/0x180 block/partitions/core.c:541
 bdev_disk_changed+0x211/0x3c0 fs/block_dev.c:1244
 __blkdev_get+0x86c/0xa30 fs/block_dev.c:1350
 blkdev_get_by_dev fs/block_dev.c:1454 [inline]
 blkdev_get_by_dev+0x26c/0x600 fs/block_dev.c:1422
 blkdev_reread_part block/ioctl.c:100 [inline]
 blkdev_common_ioctl+0x137e/0x17e0 block/ioctl.c:508
 blkdev_ioctl+0x1ef/0x6d0 block/ioctl.c:577
 block_ioctl+0xf9/0x140 fs/block_dev.c:1667
 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+0x44/0xae

The buggy address belongs to the object at ffff8880199a5080
 which belongs to the cache bdev_cache of size 2784
The buggy address is located 40 bytes inside of
 2784-byte region [ffff8880199a5080, ffff8880199a5b60)
The buggy address belongs to the page:
page:ffffea0000666800 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x199a0
head:ffffea0000666800 order:3 compound_mapcount:0 compound_pincount:0
flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000010200 dead000000000100 dead000000000122 ffff8880109bdc80
raw: 0000000000000000 00000000800b000b 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8880199a4f80: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
 ffff8880199a5000: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff8880199a5080: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                  ^
 ffff8880199a5100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8880199a5180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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