syzbot

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BUG: KASAN: slab-use-after-free in io_req_local_work_add io_uring/io_uring.c:1219 [inline]
BUG: KASAN: slab-use-after-free in __io_req_task_work_add+0x589/0x950 io_uring/io_uring.c:1287
Read of size 4 at addr ffff888032ab9904 by task iou-wrk-12380/12382

CPU: 0 UID: 0 PID: 12382 Comm: iou-wrk-12380 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xca/0x240 mm/kasan/report.c:482
 kasan_report+0x118/0x150 mm/kasan/report.c:595
 io_req_local_work_add io_uring/io_uring.c:1219 [inline]
 __io_req_task_work_add+0x589/0x950 io_uring/io_uring.c:1287
 io_req_task_work_add io_uring/io_uring.h:157 [inline]
 io_req_complete_post io_uring/io_uring.c:961 [inline]
 io_issue_sqe+0x643/0xfd0 io_uring/io_uring.c:1802
 io_wq_submit_work+0x6e9/0xb90 io_uring/io_uring.c:1908
 io_worker_handle_work+0x7cd/0x1180 io_uring/io-wq.c:650
 io_wq_worker+0x42f/0xeb0 io_uring/io-wq.c:704
 ret_from_fork+0x436/0x7d0 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>

Allocated by task 12382:
 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:330 [inline]
 __kasan_slab_alloc+0x6c/0x80 mm/kasan/common.c:356
 kasan_slab_alloc include/linux/kasan.h:250 [inline]
 slab_post_alloc_hook mm/slub.c:4191 [inline]
 slab_alloc_node mm/slub.c:4240 [inline]
 kmem_cache_alloc_noprof+0x1c1/0x3c0 mm/slub.c:4247
 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/0xa80 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:1773
 io_issue_sqe+0x165/0xfd0 io_uring/io_uring.c:1796
 io_wq_submit_work+0x6e9/0xb90 io_uring/io_uring.c:1908
 io_worker_handle_work+0x7cd/0x1180 io_uring/io-wq.c:650
 io_wq_worker+0x42f/0xeb0 io_uring/io-wq.c:704
 ret_from_fork+0x436/0x7d0 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Freed by task 12380:
 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:243 [inline]
 __kasan_mempool_poison_object+0xad/0x130 mm/kasan/common.c:533
 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/0x4f0 io_uring/msg_ring.c:80
 __io_run_local_work_loop io_uring/io_uring.c:1330 [inline]
 __io_run_local_work+0x350/0x810 io_uring/io_uring.c:1363
 io_run_local_work_locked io_uring/io_uring.c:1385 [inline]
 __do_sys_io_uring_enter io_uring/io_uring.c:3478 [inline]
 __se_sys_io_uring_enter+0x1725/0x2b20 io_uring/io_uring.c:3399
 do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:83 [inline]
 __do_fast_syscall_32+0xb6/0x2b0 arch/x86/entry/syscall_32.c:306
 do_fast_syscall_32+0x34/0x80 arch/x86/entry/syscall_32.c:331
 entry_SYSENTER_compat_after_hwframe+0x84/0x8e

The buggy address belongs to the object at ffff888032ab98c0
 which belongs to the cache io_kiocb of size 248
The buggy address is located 68 bytes inside of
 freed 248-byte region [ffff888032ab98c0, ffff888032ab99b8)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x32ab9
memcg:ffff8880334ee901
ksm flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000000 ffff8881413b9c80 ffffea0001f63740 dead000000000003
raw: 0000000000000000 00000000800c000c 00000000f5000000 ffff8880334ee901
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 12143, tgid 12142 (syz.1.1033), ts 466289495240, free_ts 459260987318
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x240/0x2a0 mm/page_alloc.c:1851
 prep_new_page mm/page_alloc.c:1859 [inline]
 get_page_from_freelist+0x21e4/0x22c0 mm/page_alloc.c:3858
 __alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:5148
 alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2416
 alloc_slab_page mm/slub.c:2492 [inline]
 allocate_slab+0x8a/0x370 mm/slub.c:2660
 new_slab mm/slub.c:2714 [inline]
 ___slab_alloc+0xbeb/0x1420 mm/slub.c:3901
 __kmem_cache_alloc_bulk mm/slub.c:5346 [inline]
 kmem_cache_alloc_bulk_noprof+0x20e/0x790 mm/slub.c:5418
 __io_alloc_req_refill+0x9d/0x280 io_uring/io_uring.c:1007
 io_alloc_req io_uring/io_uring.h:453 [inline]
 io_submit_sqes+0xbfd/0x1d30 io_uring/io_uring.c:2387
 __do_sys_io_uring_enter io_uring/io_uring.c:3465 [inline]
 __se_sys_io_uring_enter+0x2df/0x2b20 io_uring/io_uring.c:3399
 do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:83 [inline]
 __do_fast_syscall_32+0xb6/0x2b0 arch/x86/entry/syscall_32.c:306
 do_fast_syscall_32+0x34/0x80 arch/x86/entry/syscall_32.c:331
 entry_SYSENTER_compat_after_hwframe+0x84/0x8e
page last free pid 15 tgid 15 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1395 [inline]
 __free_frozen_pages+0xbc4/0xd30 mm/page_alloc.c:2895
 rcu_do_batch kernel/rcu/tree.c:2605 [inline]
 rcu_core+0xcab/0x1770 kernel/rcu/tree.c:2861
 handle_softirqs+0x283/0x870 kernel/softirq.c:579
 run_ksoftirqd+0x9b/0x100 kernel/softirq.c:968
 smpboot_thread_fn+0x53f/0xa60 kernel/smpboot.c:160
 kthread+0x70e/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x436/0x7d0 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:
 ffff888032ab9800: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 fc
 ffff888032ab9880: fc fc fc fc fc fc fc fc fa fb fb fb fb fb fb fb
>ffff888032ab9900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                   ^
 ffff888032ab9980: fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc fc
 ffff888032ab9a00: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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