Hello, syzbot found the following issue on: HEAD commit: 472e5b05 pipe: remove pipe_wait() and fix wakeup race with.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=15ae0d47900000 kernel config: https://syzkaller.appspot.com/x/.config?x=89ab6a0c48f30b49 dashboard link: https://syzkaller.appspot.com/bug?extid=12056a09a0311d758e60 compiler: gcc (GCC) 10.1.0-syz 20200507 userspace arch: i386 Unfortunately, I don't have any reproducer for this issue yet. IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+12056a09a0311d758e60@xxxxxxxxxxxxxxxxxxxxxxxxx ================================================================== 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 ffff88804eb9cb30 by task kworker/u4:8/13668 CPU: 1 PID: 13668 Comm: kworker/u4:8 Not tainted 5.9.0-rc7-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: events_unbound io_ring_exit_work Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x198/0x1fd 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_destroy_buffers fs/io_uring.c:7889 [inline] io_ring_ctx_free fs/io_uring.c:7904 [inline] io_ring_exit_work+0x363/0x6d0 fs/io_uring.c:7979 process_one_work+0x94c/0x1670 kernel/workqueue.c:2269 worker_thread+0x64c/0x1120 kernel/workqueue.c:2415 kthread+0x3b5/0x4a0 kernel/kthread.c:292 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294 Allocated by task 17016: 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:3316 [inline] kmem_cache_alloc+0x13a/0x3f0 mm/slab.c:3486 radix_tree_node_alloc.constprop.0+0x7c/0x350 lib/radix-tree.c:275 idr_get_free+0x4c5/0x940 lib/radix-tree.c:1505 idr_alloc_u32+0x170/0x2d0 lib/idr.c:46 idr_alloc+0xc2/0x130 lib/idr.c:87 io_provide_buffers fs/io_uring.c:3768 [inline] io_issue_sqe+0x48d2/0x5c50 fs/io_uring.c:5906 __io_queue_sqe+0x280/0x1160 fs/io_uring.c:6178 io_queue_sqe+0x692/0xfa0 fs/io_uring.c:6257 io_submit_sqe fs/io_uring.c:6327 [inline] io_submit_sqes+0x1759/0x23f0 fs/io_uring.c:6521 __do_sys_io_uring_enter+0xeac/0x1bd0 fs/io_uring.c:8349 do_syscall_32_irqs_on arch/x86/entry/common.c:78 [inline] __do_fast_syscall_32+0x60/0x90 arch/x86/entry/common.c:137 do_fast_syscall_32+0x2f/0x70 arch/x86/entry/common.c:160 entry_SYSENTER_compat_after_hwframe+0x4d/0x5c 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:3422 [inline] kmem_cache_free.part.0+0x74/0x1e0 mm/slab.c:3697 rcu_do_batch kernel/rcu/tree.c:2430 [inline] rcu_core+0x5ca/0x1130 kernel/rcu/tree.c:2658 __do_softirq+0x1f8/0xb23 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:2896 [inline] call_rcu+0x15e/0x7c0 kernel/rcu/tree.c:2970 radix_tree_node_free lib/radix-tree.c:309 [inline] delete_node+0x591/0x8c0 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_buffers fs/io_uring.c:3666 [inline] __io_remove_buffers fs/io_uring.c:3645 [inline] __io_destroy_buffers+0x161/0x200 fs/io_uring.c:7883 idr_for_each+0x113/0x220 lib/idr.c:208 io_destroy_buffers fs/io_uring.c:7889 [inline] io_ring_ctx_free fs/io_uring.c:7904 [inline] io_ring_exit_work+0x363/0x6d0 fs/io_uring.c:7979 process_one_work+0x94c/0x1670 kernel/workqueue.c:2269 worker_thread+0x64c/0x1120 kernel/workqueue.c:2415 kthread+0x3b5/0x4a0 kernel/kthread.c:292 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294 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:2896 [inline] call_rcu+0x15e/0x7c0 kernel/rcu/tree.c:2970 radix_tree_node_free lib/radix-tree.c:309 [inline] radix_tree_shrink lib/radix-tree.c:535 [inline] delete_node+0x37a/0x8c0 lib/radix-tree.c:553 __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+0x1c7/0x2d0 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+0x2fd2/0x3b70 kernel/exit.c:1315 do_wait_thread kernel/exit.c:1378 [inline] do_wait+0x376/0xa00 kernel/exit.c:1449 kernel_wait4+0x14c/0x260 kernel/exit.c:1621 do_syscall_32_irqs_on arch/x86/entry/common.c:78 [inline] __do_fast_syscall_32+0x60/0x90 arch/x86/entry/common.c:137 do_fast_syscall_32+0x2f/0x70 arch/x86/entry/common.c:160 entry_SYSENTER_compat_after_hwframe+0x4d/0x5c The buggy address belongs to the object at ffff88804eb9cb00 which belongs to the cache radix_tree_node of size 576 The buggy address is located 48 bytes inside of 576-byte region [ffff88804eb9cb00, ffff88804eb9cd40) The buggy address belongs to the page: page:00000000a35d3b6e refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff88804eb9cffb pfn:0x4eb9c flags: 0xfffe0000000200(slab) raw: 00fffe0000000200 ffffea00013ab388 ffffea0002927748 ffff8880aa06f000 raw: ffff88804eb9cffb ffff88804eb9c000 0000000100000005 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff88804eb9ca00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88804eb9ca80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff88804eb9cb00: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff88804eb9cb80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88804eb9cc00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ================================================================== --- This report is generated by a bot. 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