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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+0x1e3/0x4a0 block/genhd.c:207
Read of size 8 at addr ffff888016a65c28 by task syz-executor.0/10446

CPU: 1 PID: 10446 Comm: syz-executor.0 Not tainted 5.12.0-rc1-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+0x125/0x19e lib/dump_stack.c:120
 print_address_description+0x5f/0x3a0 mm/kasan/report.c:232
 __kasan_report mm/kasan/report.c:399 [inline]
 kasan_report+0x15e/0x210 mm/kasan/report.c:416
 bdev_nr_sectors include/linux/genhd.h:266 [inline]
 disk_part_iter_next+0x1e3/0x4a0 block/genhd.c:207
 blk_drop_partitions+0xab/0x250 block/partitions/core.c:543
 bdev_disk_changed+0x128/0x3c0 fs/block_dev.c:1237
 __loop_clr_fd+0x773/0xa20 drivers/block/loop.c:1271
 __blkdev_put+0x519/0x670 fs/block_dev.c:1579
 blkdev_put+0x2cd/0x440 fs/block_dev.c:1632
 blkdev_close+0x7a/0xa0 fs/block_dev.c:1640
 __fput+0x352/0x7b0 fs/file_table.c:280
 task_work_run+0x146/0x1c0 kernel/task_work.c:140
 tracehook_notify_resume include/linux/tracehook.h:189 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:174 [inline]
 exit_to_user_mode_prepare+0x10b/0x1e0 kernel/entry/common.c:208
 __syscall_exit_to_user_mode_work kernel/entry/common.c:290 [inline]
 syscall_exit_to_user_mode+0x48/0x180 kernel/entry/common.c:301
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x41920b
Code: 0f 05 48 3d 00 f0 ff ff 77 45 c3 0f 1f 40 00 48 83 ec 18 89 7c 24 0c e8 63 fc ff ff 8b 7c 24 0c 41 89 c0 b8 03 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 35 44 89 c7 89 44 24 0c e8 a1 fc ff ff 8b 44
RSP: 002b:00007f0e5adbef90 EFLAGS: 00000293 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 0000000020001340 RCX: 000000000041920b
RDX: 0000000000000000 RSI: 0000000000004c01 RDI: 0000000000000005
RBP: 00007f0e5adbf6bc R08: 0000000000000000 R09: 0000000020000040
R10: 0000000001008000 R11: 0000000000000293 R12: ffffffffffffffff
R13: 0000000000000016 R14: 00007f0e5adbf000 R15: 00000000200013c0

Allocated by task 9837:
 kasan_save_stack mm/kasan/common.c:38 [inline]
 kasan_set_track mm/kasan/common.c:46 [inline]
 set_alloc_info mm/kasan/common.c:427 [inline]
 __kasan_slab_alloc+0x8f/0xc0 mm/kasan/common.c:460
 kasan_slab_alloc include/linux/kasan.h:223 [inline]
 slab_post_alloc_hook mm/slab.h:516 [inline]
 slab_alloc_node mm/slub.c:2907 [inline]
 slab_alloc mm/slub.c:2915 [inline]
 kmem_cache_alloc+0x1c8/0x330 mm/slub.c:2920
 bdev_alloc_inode+0x17/0x80 fs/block_dev.c:786
 alloc_inode fs/inode.c:234 [inline]
 new_inode_pseudo+0x61/0x220 fs/inode.c:928
 new_inode+0x25/0x1d0 fs/inode.c:957
 bdev_alloc+0x20/0x290 fs/block_dev.c:876
 add_partition+0x13c/0x790 block/partitions/core.c:348
 bdev_add_partition+0x1a8/0x1f0 block/partitions/core.c:451
 blkpg_do_ioctl+0x29d/0x300 block/ioctl.c:43
 blkpg_ioctl block/ioctl.c:60 [inline]
 blkdev_ioctl+0x36d/0x600 block/ioctl.c:548
 block_ioctl+0xae/0xf0 fs/block_dev.c:1658
 vfs_ioctl fs/ioctl.c:48 [inline]
 __do_sys_ioctl fs/ioctl.c:753 [inline]
 __se_sys_ioctl+0xfb/0x170 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 8404:
 kasan_save_stack mm/kasan/common.c:38 [inline]
 kasan_set_track+0x3d/0x70 mm/kasan/common.c:46
 kasan_set_free_info+0x1f/0x40 mm/kasan/generic.c:357
 ____kasan_slab_free+0x100/0x140 mm/kasan/common.c:360
 kasan_slab_free include/linux/kasan.h:199 [inline]
 slab_free_hook mm/slub.c:1562 [inline]
 slab_free_freelist_hook+0x13a/0x200 mm/slub.c:1600
 slab_free mm/slub.c:3161 [inline]
 kmem_cache_free+0x85/0x170 mm/slub.c:3177
 rcu_do_batch kernel/rcu/tree.c:2559 [inline]
 rcu_core+0x7a0/0x1220 kernel/rcu/tree.c:2794
 __do_softirq+0x318/0x714 kernel/softirq.c:345

Last potentially related work creation:
 kasan_save_stack+0x27/0x50 mm/kasan/common.c:38
 kasan_record_aux_stack+0xee/0x120 mm/kasan/generic.c:345
 __call_rcu kernel/rcu/tree.c:3039 [inline]
 call_rcu+0x12f/0x8a0 kernel/rcu/tree.c:3114
 disk_part_iter_exit block/genhd.c:236 [inline]
 disk_part_iter_next+0x61/0x4a0 block/genhd.c:203
 blk_drop_partitions+0x1c5/0x250 block/partitions/core.c:543
 bdev_disk_changed+0x128/0x3c0 fs/block_dev.c:1237
 loop_reread_partitions drivers/block/loop.c:655 [inline]
 loop_set_status+0xa2a/0xd00 drivers/block/loop.c:1418
 lo_ioctl+0xb56/0x20b0 drivers/block/loop.c:1528
 blkdev_ioctl+0x2e1/0x600 block/ioctl.c:583
 block_ioctl+0xae/0xf0 fs/block_dev.c:1658
 vfs_ioctl fs/ioctl.c:48 [inline]
 __do_sys_ioctl fs/ioctl.c:753 [inline]
 __se_sys_ioctl+0xfb/0x170 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 ffff888016a65c00
 which belongs to the cache bdev_cache of size 2792
The buggy address is located 40 bytes inside of
 2792-byte region [ffff888016a65c00, ffff888016a666e8)
The buggy address belongs to the page:
page:000000005ec36f1a refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x16a60
head:000000005ec36f1a order:3 compound_mapcount:0 compound_pincount:0
flags: 0xfff00000010200(slab|head)
raw: 00fff00000010200 dead000000000100 dead000000000122 ffff888140006c80
raw: 0000000000000000 00000000800b000b 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff888016a65b00: 00 00 00 00 00 00 00 00 00 00 00 00 00 fc fc fc
 ffff888016a65b80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff888016a65c00: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                  ^
 ffff888016a65c80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888016a65d00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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