================================================================== BUG: KASAN: use-after-free in radix_tree_next_slot include/linux/radix-tree.h:421 [inline] BUG: KASAN: use-after-free in idr_for_each+0x206/0x220 lib/idr.c:202 Read of size 8 at addr ffff8880791868b8 by task syz-executor.2/7730 CPU: 1 PID: 7730 Comm: syz-executor.2 Not tainted 5.8.0-next-20200814-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x18f/0x20d lib/dump_stack.c:118 print_address_description.constprop.0.cold+0xae/0x497 mm/kasan/report.c:383 __kasan_report mm/kasan/report.c:513 [inline] kasan_report.cold+0x1f/0x37 mm/kasan/report.c:530 radix_tree_next_slot include/linux/radix-tree.h:421 [inline] idr_for_each+0x206/0x220 lib/idr.c:202 io_ring_ctx_wait_and_kill+0x374/0x600 fs/io_uring.c:7810 io_uring_release+0x3e/0x50 fs/io_uring.c:7829 __fput+0x285/0x920 fs/file_table.c:281 task_work_run+0xdd/0x190 kernel/task_work.c:135 exit_task_work include/linux/task_work.h:25 [inline] do_exit+0xb7d/0x29f0 kernel/exit.c:806 do_group_exit+0x125/0x310 kernel/exit.c:903 get_signal+0x40b/0x1ee0 kernel/signal.c:2743 arch_do_signal+0x82/0x2520 arch/x86/kernel/signal.c:811 exit_to_user_mode_loop kernel/entry/common.c:135 [inline] exit_to_user_mode_prepare+0x15d/0x1c0 kernel/entry/common.c:166 syscall_exit_to_user_mode+0x59/0x2b0 kernel/entry/common.c:241 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x45d239 Code: Bad RIP value. RSP: 002b:00007f4c31e01cf8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca RAX: 0000000000000001 RBX: 000000000118cfe8 RCX: 000000000045d239 RDX: 00000000000f4240 RSI: 0000000000000081 RDI: 000000000118cfec RBP: 000000000118cfe0 R08: 0000000000000009 R09: 0000000000000000 R10: ffffffffffffffff R11: 0000000000000246 R12: 000000000118cfec R13: 00007ffec499f74f R14: 00007f4c31e029c0 R15: 000000000118cfec Allocated by task 7713: kasan_save_stack+0x1b/0x40 mm/kasan/common.c:48 kasan_set_track mm/kasan/common.c:56 [inline] __kasan_kmalloc.constprop.0+0xbf/0xd0 mm/kasan/common.c:461 slab_post_alloc_hook mm/slab.h:518 [inline] slab_alloc mm/slab.c:3312 [inline] kmem_cache_alloc+0x138/0x3a0 mm/slab.c:3482 radix_tree_node_alloc.constprop.0+0x7c/0x320 lib/radix-tree.c:275 idr_get_free+0x4b0/0x8e0 lib/radix-tree.c:1505 idr_alloc_u32+0x170/0x2d0 lib/idr.c:46 idr_alloc_cyclic+0x102/0x230 lib/idr.c:125 io_register_personality fs/io_uring.c:8454 [inline] __io_uring_register fs/io_uring.c:8575 [inline] __do_sys_io_uring_register+0x606/0x33f0 fs/io_uring.c:8615 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xa9 Freed by task 16: kasan_save_stack+0x1b/0x40 mm/kasan/common.c:48 kasan_set_track+0x1c/0x30 mm/kasan/common.c:56 kasan_set_free_info+0x1b/0x30 mm/kasan/generic.c:355 __kasan_slab_free+0xd8/0x120 mm/kasan/common.c:422 __cache_free mm/slab.c:3418 [inline] kmem_cache_free.part.0+0x67/0x1f0 mm/slab.c:3693 rcu_do_batch kernel/rcu/tree.c:2428 [inline] rcu_core+0x5c7/0x1190 kernel/rcu/tree.c:2656 __do_softirq+0x2de/0xa24 kernel/softirq.c:298 Last call_rcu(): kasan_save_stack+0x1b/0x40 mm/kasan/common.c:48 kasan_record_aux_stack+0x82/0xb0 mm/kasan/generic.c:346 __call_rcu kernel/rcu/tree.c:2894 [inline] call_rcu+0x14f/0x7e0 kernel/rcu/tree.c:2968 radix_tree_node_free lib/radix-tree.c:309 [inline] delete_node+0x587/0x8a0 lib/radix-tree.c:572 __radix_tree_delete+0x190/0x370 lib/radix-tree.c:1378 radix_tree_delete_item+0xe7/0x230 lib/radix-tree.c:1429 io_remove_personalities+0x1b/0xb0 fs/io_uring.c:7769 idr_for_each+0x113/0x220 lib/idr.c:208 io_ring_ctx_wait_and_kill+0x374/0x600 fs/io_uring.c:7810 io_uring_release+0x3e/0x50 fs/io_uring.c:7829 __fput+0x285/0x920 fs/file_table.c:281 task_work_run+0xdd/0x190 kernel/task_work.c:135 exit_task_work include/linux/task_work.h:25 [inline] do_exit+0xb7d/0x29f0 kernel/exit.c:806 do_group_exit+0x125/0x310 kernel/exit.c:903 get_signal+0x40b/0x1ee0 kernel/signal.c:2743 arch_do_signal+0x82/0x2520 arch/x86/kernel/signal.c:811 exit_to_user_mode_loop kernel/entry/common.c:135 [inline] exit_to_user_mode_prepare+0x15d/0x1c0 kernel/entry/common.c:166 syscall_exit_to_user_mode+0x59/0x2b0 kernel/entry/common.c:241 entry_SYSCALL_64_after_hwframe+0x44/0xa9 Second to last call_rcu(): kasan_save_stack+0x1b/0x40 mm/kasan/common.c:48 kasan_record_aux_stack+0x82/0xb0 mm/kasan/generic.c:346 __call_rcu kernel/rcu/tree.c:2894 [inline] call_rcu+0x14f/0x7e0 kernel/rcu/tree.c:2968 radix_tree_node_free lib/radix-tree.c:309 [inline] delete_node+0xe5/0x8a0 lib/radix-tree.c:572 __radix_tree_delete+0x190/0x370 lib/radix-tree.c:1378 radix_tree_delete_item+0xe7/0x230 lib/radix-tree.c:1429 free_pid+0xa1/0x260 kernel/pid.c:151 __change_pid+0x1d2/0x2d0 kernel/pid.c:352 __unhash_process kernel/exit.c:77 [inline] __exit_signal kernel/exit.c:147 [inline] release_task+0xd29/0x14d0 kernel/exit.c:198 wait_task_zombie kernel/exit.c:1088 [inline] wait_consider_task+0x2fb3/0x3b20 kernel/exit.c:1315 do_wait_thread kernel/exit.c:1378 [inline] do_wait+0x36a/0x9e0 kernel/exit.c:1449 kernel_wait4+0x14c/0x260 kernel/exit.c:1604 __do_sys_wait4+0x13f/0x150 kernel/exit.c:1632 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xa9 The buggy address belongs to the object at ffff888079186880 which belongs to the cache radix_tree_node of size 576 The buggy address is located 56 bytes inside of 576-byte region [ffff888079186880, ffff888079186ac0) The buggy address belongs to the page: page:0000000091d81daf refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff888079186ffb pfn:0x79186 flags: 0xfffe0000000200(slab) raw: 00fffe0000000200 ffffea0001e45548 ffffea0001e46648 ffff8880aa06f000 raw: ffff888079186ffb ffff888079186040 0000000100000005 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff888079186780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888079186800: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff888079186880: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff888079186900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888079186980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================