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BUG: KASAN: slab-use-after-free in jfs_lazycommit+0x749/0xaa0
Read of size 4 at addr ffff88810c8a5094 by task jfsCommit/124

CPU: 1 UID: 0 PID: 124 Comm: jfsCommit 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+0xe8/0x150
 print_address_description+0x55/0x1e0
 print_report+0x58/0x70
 kasan_report+0x117/0x150
 jfs_lazycommit+0x749/0xaa0
 kthread+0x388/0x470
 ret_from_fork+0x514/0xb70
 ret_from_fork_asm+0x1a/0x30
 </TASK>

Allocated by task 19505:
 kasan_save_track+0x3e/0x80
 __kasan_kmalloc+0x93/0xb0
 __kmalloc_cache_noprof+0x31c/0x660
 jfs_fill_super+0xc2/0xd80
 get_tree_bdev_flags+0x431/0x4f0
 vfs_get_tree+0x92/0x2a0
 do_new_mount+0x341/0xd30
 __se_sys_mount+0x31d/0x420
 do_syscall_64+0x15f/0xf80
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 18557:
 kasan_save_track+0x3e/0x80
 kasan_save_free_info+0x46/0x50
 __kasan_slab_free+0x5c/0x80
 kfree+0x1c5/0x640
 generic_shutdown_super+0x13d/0x2d0
 kill_block_super+0x44/0x90
 deactivate_locked_super+0xbc/0x130
 cleanup_mnt+0x437/0x4d0
 task_work_run+0x1d9/0x270
 exit_to_user_mode_loop+0xf3/0x4d0
 do_syscall_64+0x33e/0xf80
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff88810c8a5000
 which belongs to the cache kmalloc-256 of size 256
The buggy address is located 148 bytes inside of
 freed 256-byte region [ffff88810c8a5000, ffff88810c8a5100)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff88810c8a5800 pfn:0x10c8a4
head: order:1 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0x17ff00000000240(workingset|head|node=0|zone=2|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 017ff00000000240 ffff888100041b40 ffffea00042bc710 ffff888100040708
raw: ffff88810c8a5800 000000080010000c 00000000f5000000 0000000000000000
head: 017ff00000000240 ffff888100041b40 ffffea00042bc710 ffff888100040708
head: ffff88810c8a5800 000000080010000c 00000000f5000000 0000000000000000
head: 017ff00000000001 ffffffffffffff81 00000000ffffffff 00000000ffffffff
head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000002
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 1, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 19508, tgid 19507 (syz.1.1815), ts 573583192568, free_ts 573451093742
 post_alloc_hook+0x231/0x280
 get_page_from_freelist+0x24ba/0x2540
 __alloc_frozen_pages_noprof+0x18d/0x380
 allocate_slab+0x77/0x660
 refill_objects+0x339/0x3d0
 __pcs_replace_empty_main+0x321/0x720
 __kmalloc_cache_noprof+0x392/0x660
 __se_sys_memfd_create+0x21d/0x410
 do_syscall_64+0x15f/0xf80
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
page last free pid 19503 tgid 19502 stack trace:
 __free_frozen_pages+0xbc7/0xd30
 __slab_free+0x274/0x2c0
 qlist_free_all+0x99/0x100
 kasan_quarantine_reduce+0x148/0x160
 __kasan_slab_alloc+0x22/0x80
 __kmalloc_noprof+0x316/0x760
 iter_file_splice_write+0x1da/0x10f0
 direct_splice_actor+0x101/0x160
 splice_direct_to_actor+0x53a/0xc70
 do_splice_direct+0x195/0x290
 do_sendfile+0x535/0x7d0
 __se_sys_sendfile64+0x144/0x1a0
 do_syscall_64+0x15f/0xf80
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff88810c8a4f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88810c8a5000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88810c8a5080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                         ^
 ffff88810c8a5100: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88810c8a5180: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
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