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BUG: KASAN: slab-use-after-free in sync_blockdev_nowait+0x3a/0x60
Read of size 8 at addr ffff88803ec2dc38 by task syz-executor/11546

CPU: 1 UID: 0 PID: 11546 Comm: syz-executor 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
 sync_blockdev_nowait+0x3a/0x60
 sync_filesystem+0x149/0x230
 generic_shutdown_super+0x6f/0x2c0
 bch2_kill_sb+0x41/0x50
 deactivate_locked_super+0xbc/0x130
 cleanup_mnt+0x425/0x4c0
 task_work_run+0x1d4/0x260
 exit_to_user_mode_loop+0xec/0x110
 do_syscall_64+0x2bd/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f379118ff17
Code: a8 ff ff ff f7 d8 64 89 01 48 83 c8 ff c3 0f 1f 44 00 00 31 f6 e9 09 00 00 00 66 0f 1f 84 00 00 00 00 00 b8 a6 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 01 c3 48 c7 c2 a8 ff ff ff f7 d8 64 89 02 b8
RSP: 002b:00007ffef69dfe78 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 00007f3791211c05 RCX: 00007f379118ff17
RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007ffef69dff30
RBP: 00007ffef69dff30 R08: 0000000000000000 R09: 0000000000000000
R10: 00000000ffffffff R11: 0000000000000246 R12: 00007ffef69e0fc0
R13: 00007f3791211c05 R14: 000000000002e3a3 R15: 00007ffef69e1000
 </TASK>

Allocated by task 12149:
 kasan_save_track+0x3e/0x80
 __kasan_slab_alloc+0x6c/0x80
 kmem_cache_alloc_lru_noprof+0x1c6/0x3d0
 bdev_alloc_inode+0x29/0x90
 alloc_inode+0x6a/0x1b0
 new_inode+0x22/0x170
 bdev_alloc+0x26/0x380
 __alloc_disk_node+0x11c/0x550
 __blk_mq_alloc_disk+0x196/0x340
 loop_add+0x411/0xad0
 loop_control_ioctl+0x128/0x5a0
 __se_sys_ioctl+0xfc/0x170
 do_syscall_64+0xfa/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 15:
 kasan_save_track+0x3e/0x80
 kasan_save_free_info+0x46/0x50
 __kasan_slab_free+0x5b/0x80
 kmem_cache_free+0x18f/0x400
 rcu_core+0xcab/0x1770
 handle_softirqs+0x286/0x870
 run_ksoftirqd+0x9b/0x100
 smpboot_thread_fn+0x542/0xa60
 kthread+0x711/0x8a0
 ret_from_fork+0x3fc/0x770
 ret_from_fork_asm+0x1a/0x30

Last potentially related work creation:
 kasan_save_stack+0x3e/0x60
 kasan_record_aux_stack+0xbd/0xd0
 call_rcu+0x157/0x9c0
 evict+0x847/0x9c0
 device_release+0x9c/0x1c0
 kobject_put+0x22b/0x480
 loop_control_ioctl+0x4ac/0x5a0
 __se_sys_ioctl+0xfc/0x170
 do_syscall_64+0xfa/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff88803ec2dc00
 which belongs to the cache bdev_cache of size 2792
The buggy address is located 56 bytes inside of
 freed 2792-byte region [ffff88803ec2dc00, ffff88803ec2e6e8)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff88803ec2c500 pfn:0x3ec28
head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
memcg:ffff88802ab34601
flags: 0xfff00000000040(head|node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000040 ffff88801bee4280 dead000000000122 0000000000000000
raw: ffff88803ec2c500 00000000800b000a 00000000f5000000 ffff88802ab34601
head: 00fff00000000040 ffff88801bee4280 dead000000000122 0000000000000000
head: ffff88803ec2c500 00000000800b000a 00000000f5000000 ffff88802ab34601
head: 00fff00000000003 ffffea0000fb0a01 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 Reclaimable, gfp_mask 0xd20d0(__GFP_RECLAIMABLE|__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 11913, tgid 11910 (syz.2.935), ts 183240556042, free_ts 146095188473
 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
 kmem_cache_alloc_lru_noprof+0x288/0x3d0
 bdev_alloc_inode+0x29/0x90
 alloc_inode+0x6a/0x1b0
 new_inode+0x22/0x170
 bdev_alloc+0x26/0x380
 __alloc_disk_node+0x11c/0x550
 __blk_mq_alloc_disk+0x196/0x340
 loop_add+0x411/0xad0
 loop_control_ioctl+0x128/0x5a0
 __se_sys_ioctl+0xfc/0x170
page last free pid 10113 tgid 10112 stack trace:
 __free_pages_ok+0xa83/0xbe0
 free_large_kmalloc+0x13a/0x1f0
 __btree_node_data_free+0x2bb/0x3a0
 btree_node_data_free+0x13f/0x340
 bch2_fs_btree_cache_exit+0x9c1/0x13c0
 bch2_fs_release+0x2bb/0x830
 kobject_put+0x22b/0x480
 bch2_fs_get_tree+0xb6e/0x1520
 vfs_get_tree+0x92/0x2b0
 do_new_mount+0x2a2/0x9e0
 __se_sys_mount+0x317/0x410
 do_syscall_64+0xfa/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff88803ec2db00: 00 00 00 00 00 00 00 00 00 00 00 00 00 fc fc fc
 ffff88803ec2db80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88803ec2dc00: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                        ^
 ffff88803ec2dc80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88803ec2dd00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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