syzbot

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BUG: KASAN: slab-use-after-free in io_req_local_work_add io_uring/io_uring.c:1184 [inline]
BUG: KASAN: slab-use-after-free in __io_req_task_work_add+0x589/0x950 io_uring/io_uring.c:1252
Read of size 4 at addr ffff88804f04f044 by task iou-wrk-19354/19356

CPU: 1 UID: 0 PID: 19356 Comm: iou-wrk-19354 Not tainted 6.16.0-rc4-syzkaller-00108-g17bbde2e1716 #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:408 [inline]
 print_report+0xd2/0x2b0 mm/kasan/report.c:521
 kasan_report+0x118/0x150 mm/kasan/report.c:634
 io_req_local_work_add io_uring/io_uring.c:1184 [inline]
 __io_req_task_work_add+0x589/0x950 io_uring/io_uring.c:1252
 io_msg_remote_post io_uring/msg_ring.c:103 [inline]
 io_msg_data_remote io_uring/msg_ring.c:133 [inline]
 __io_msg_ring_data+0x820/0xaa0 io_uring/msg_ring.c:151
 io_msg_ring_data io_uring/msg_ring.c:173 [inline]
 io_msg_ring+0x134/0xa00 io_uring/msg_ring.c:314
 __io_issue_sqe+0x17e/0x4b0 io_uring/io_uring.c:1739
 io_issue_sqe+0x165/0xfd0 io_uring/io_uring.c:1762
 io_wq_submit_work+0x6e9/0xb90 io_uring/io_uring.c:1874
 io_worker_handle_work+0x7cd/0x1180 io_uring/io-wq.c:642
 io_wq_worker+0x42f/0xeb0 io_uring/io-wq.c:696
 ret_from_fork+0x3fc/0x770 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>

Allocated by task 19354:
 kasan_save_stack mm/kasan/common.c:47 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:68
 unpoison_slab_object mm/kasan/common.c:319 [inline]
 __kasan_slab_alloc+0x6c/0x80 mm/kasan/common.c:345
 kasan_slab_alloc include/linux/kasan.h:250 [inline]
 slab_post_alloc_hook mm/slub.c:4148 [inline]
 slab_alloc_node mm/slub.c:4197 [inline]
 kmem_cache_alloc_noprof+0x1c1/0x3c0 mm/slub.c:4204
 io_msg_get_kiocb io_uring/msg_ring.c:117 [inline]
 io_msg_data_remote io_uring/msg_ring.c:126 [inline]
 __io_msg_ring_data+0x47b/0xaa0 io_uring/msg_ring.c:151
 io_msg_ring_data io_uring/msg_ring.c:173 [inline]
 io_msg_ring+0x134/0xa00 io_uring/msg_ring.c:314
 __io_issue_sqe+0x17e/0x4b0 io_uring/io_uring.c:1739
 io_issue_sqe+0x165/0xfd0 io_uring/io_uring.c:1762
 io_queue_sqe io_uring/io_uring.c:1969 [inline]
 io_submit_sqe io_uring/io_uring.c:2225 [inline]
 io_submit_sqes+0xa38/0x1c50 io_uring/io_uring.c:2338
 __do_sys_io_uring_enter io_uring/io_uring.c:3405 [inline]
 __se_sys_io_uring_enter+0x2df/0x2b20 io_uring/io_uring.c:3339
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 19354:
 kasan_save_stack mm/kasan/common.c:47 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:68
 kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:576
 poison_slab_object mm/kasan/common.c:247 [inline]
 __kasan_mempool_poison_object+0xad/0x130 mm/kasan/common.c:522
 kasan_mempool_poison_object include/linux/kasan.h:360 [inline]
 io_alloc_cache_put io_uring/alloc_cache.h:23 [inline]
 io_msg_tw_complete+0x12c/0x510 io_uring/msg_ring.c:80
 __io_run_local_work_loop io_uring/io_uring.c:1295 [inline]
 __io_run_local_work+0x350/0x810 io_uring/io_uring.c:1328
 io_run_local_work_locked io_uring/io_uring.c:1350 [inline]
 __do_sys_io_uring_enter io_uring/io_uring.c:3418 [inline]
 __se_sys_io_uring_enter+0x1725/0x2b20 io_uring/io_uring.c:3339
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff88804f04f000
 which belongs to the cache io_kiocb of size 248
The buggy address is located 68 bytes inside of
 freed 248-byte region [ffff88804f04f000, ffff88804f04f0f8)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x4f04f
memcg:ffff88805b8eca01
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000000 ffff88801ff1e3c0 ffffea0001f19540 0000000000000008
raw: 0000000000000000 00000000000c000c 00000000f5000000 ffff88805b8eca01
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x52cc0(GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP), pid 19106, tgid 19105 (syz.3.4309), ts 738394506846, free_ts 738346896625
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x240/0x2a0 mm/page_alloc.c:1704
 prep_new_page mm/page_alloc.c:1712 [inline]
 get_page_from_freelist+0x21e4/0x22c0 mm/page_alloc.c:3669
 __alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:4959
 alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2419
 alloc_slab_page mm/slub.c:2451 [inline]
 allocate_slab+0x8a/0x3b0 mm/slub.c:2619
 new_slab mm/slub.c:2673 [inline]
 ___slab_alloc+0xbfc/0x1480 mm/slub.c:3859
 __kmem_cache_alloc_bulk mm/slub.c:5294 [inline]
 kmem_cache_alloc_bulk_noprof+0x20e/0x790 mm/slub.c:5366
 __io_alloc_req_refill+0x9d/0x280 io_uring/io_uring.c:972
 io_alloc_req io_uring/io_uring.h:447 [inline]
 io_submit_sqes+0xc31/0x1c50 io_uring/io_uring.c:2327
 __do_sys_io_uring_enter io_uring/io_uring.c:3405 [inline]
 __se_sys_io_uring_enter+0x2df/0x2b20 io_uring/io_uring.c:3339
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
page last free pid 6405 tgid 6405 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1248 [inline]
 __free_frozen_pages+0xc71/0xe70 mm/page_alloc.c:2706
 pagetable_free include/linux/mm.h:2879 [inline]
 pagetable_dtor_free include/linux/mm.h:2977 [inline]
 __tlb_remove_table+0x2d2/0x3b0 include/asm-generic/tlb.h:220
 __tlb_remove_table_free mm/mmu_gather.c:227 [inline]
 tlb_remove_table_rcu+0x85/0x100 mm/mmu_gather.c:290
 rcu_do_batch kernel/rcu/tree.c:2576 [inline]
 rcu_core+0xca5/0x1710 kernel/rcu/tree.c:2832
 handle_softirqs+0x286/0x870 kernel/softirq.c:579
 do_softirq+0xec/0x180 kernel/softirq.c:480
 __local_bh_enable_ip+0x17d/0x1c0 kernel/softirq.c:407
 spin_unlock_bh include/linux/spinlock.h:396 [inline]
 batadv_nc_purge_paths+0x318/0x3b0 net/batman-adv/network-coding.c:471
 batadv_nc_worker+0x328/0x610 net/batman-adv/network-coding.c:720
 process_one_work kernel/workqueue.c:3238 [inline]
 process_scheduled_works+0xade/0x17b0 kernel/workqueue.c:3321
 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3402
 kthread+0x70e/0x8a0 kernel/kthread.c:464
 ret_from_fork+0x3fc/0x770 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Memory state around the buggy address:
 ffff88804f04ef00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88804f04ef80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff88804f04f000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                           ^
 ffff88804f04f080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fc
 ffff88804f04f100: fc fc fc fc fc fc fc fc 00 00 00 00 00 00 00 00
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