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BUG: KASAN: slab-use-after-free in __io_req_task_work_add+0x589/0x950
Read of size 4 at addr ffff888115227544 by task iou-wrk-19423/19438

CPU: 1 UID: 0 PID: 19438 Comm: iou-wrk-19423 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
 __io_req_task_work_add+0x589/0x950
 io_issue_sqe+0x643/0xfd0
 io_wq_submit_work+0x6e9/0xb90
 io_worker_handle_work+0x7cd/0x1180
 io_wq_worker+0x42f/0xeb0
 ret_from_fork+0x3fc/0x770
 ret_from_fork_asm+0x1a/0x30
 </TASK>

Allocated by task 19438:
 kasan_save_track+0x3e/0x80
 __kasan_slab_alloc+0x6c/0x80
 kmem_cache_alloc_noprof+0x1c1/0x3c0
 __io_msg_ring_data+0x47b/0xa80
 io_msg_ring+0x134/0xa00
 __io_issue_sqe+0x181/0x4b0
 io_issue_sqe+0x165/0xfd0
 io_wq_submit_work+0x6e9/0xb90
 io_worker_handle_work+0x7cd/0x1180
 io_wq_worker+0x42f/0xeb0
 ret_from_fork+0x3fc/0x770
 ret_from_fork_asm+0x1a/0x30

Freed by task 19423:
 kasan_save_track+0x3e/0x80
 kasan_save_free_info+0x46/0x50
 __kasan_mempool_poison_object+0xad/0x130
 io_msg_tw_complete+0x12c/0x4f0
 __io_run_local_work+0x353/0x810
 __se_sys_io_uring_enter+0x1725/0x2b20
 do_syscall_64+0xfa/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff888115227500
 which belongs to the cache io_kiocb of size 248
The buggy address is located 68 bytes inside of
 freed 248-byte region [ffff888115227500, ffff8881152275f8)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x115226
head: order:1 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
memcg:ffff88810797bd01
flags: 0x57ff00000000040(head|node=1|zone=2|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 057ff00000000040 ffff88801c32f640 dead000000000122 0000000000000000
raw: 0000000000000000 0000000080150015 00000000f5000000 ffff88810797bd01
head: 057ff00000000040 ffff88801c32f640 dead000000000122 0000000000000000
head: 0000000000000000 0000000080150015 00000000f5000000 ffff88810797bd01
head: 057ff00000000001 ffffea0004548981 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 19423, tgid 19422 (syz.2.2766), ts 389678637050, free_ts 387838491212
 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_bulk_noprof+0x20e/0x790
 __io_alloc_req_refill+0x9d/0x280
 io_submit_sqes+0xbfd/0x1d30
 __se_sys_io_uring_enter+0x2df/0x2b20
 do_syscall_64+0xfa/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
page last free pid 13 tgid 13 stack trace:
 __free_frozen_pages+0xbc4/0xd30
 rcu_core+0xcab/0x1770
 handle_softirqs+0x286/0x870
 do_softirq+0xec/0x180
 __local_bh_enable_ip+0x17d/0x1c0
 batadv_nc_purge_paths+0x318/0x3b0
 batadv_nc_worker+0x328/0x610
 process_scheduled_works+0xae1/0x17b0
 worker_thread+0x8a0/0xda0
 kthread+0x711/0x8a0
 ret_from_fork+0x3fc/0x770
 ret_from_fork_asm+0x1a/0x30

Memory state around the buggy address:
 ffff888115227400: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 fc
 ffff888115227480: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff888115227500: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                           ^
 ffff888115227580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fc
 ffff888115227600: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
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