================================================================== BUG: KASAN: use-after-free in mutex_spin_on_owner+0x2a6/0x310 kernel/locking/mutex.c:580 Read of size 4 at addr ffff8881ca97bf38 by task syz-executor.1/316 CPU: 1 PID: 316 Comm: syz-executor.1 Not tainted 5.4.219-syzkaller-00002-ga0eae55f26a0 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x1d8/0x241 lib/dump_stack.c:118 print_address_description+0x8c/0x630 mm/kasan/report.c:384 __kasan_report+0xf6/0x130 mm/kasan/report.c:516 kasan_report+0x30/0x60 mm/kasan/common.c:653 mutex_spin_on_owner+0x2a6/0x310 kernel/locking/mutex.c:580 mutex_optimistic_spin kernel/locking/mutex.c:685 [inline] __mutex_lock_common kernel/locking/mutex.c:1063 [inline] __mutex_lock+0x7c5/0x10d0 kernel/locking/mutex.c:1114 mutex_lock_killable+0xd9/0x120 kernel/locking/mutex.c:1348 loop_clr_fd drivers/block/loop.c:1321 [inline] lo_ioctl+0x2b8/0x2310 drivers/block/loop.c:1709 __blkdev_driver_ioctl block/ioctl.c:304 [inline] blkdev_ioctl+0x8d7/0x2cc0 block/ioctl.c:609 block_ioctl+0xa8/0xe0 fs/block_dev.c:1974 do_vfs_ioctl+0x744/0x1730 fs/ioctl.c:47 ksys_ioctl fs/ioctl.c:742 [inline] __do_sys_ioctl fs/ioctl.c:749 [inline] __se_sys_ioctl fs/ioctl.c:747 [inline] __x64_sys_ioctl+0xd4/0x110 fs/ioctl.c:747 do_syscall_64+0xcb/0x1c0 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x5c/0xc1 Allocated by task 9352: save_stack mm/kasan/common.c:70 [inline] set_track mm/kasan/common.c:78 [inline] __kasan_kmalloc+0x131/0x1e0 mm/kasan/common.c:529 slab_post_alloc_hook mm/slab.h:584 [inline] slab_alloc_node mm/slub.c:2829 [inline] slab_alloc mm/slub.c:2837 [inline] kmem_cache_alloc+0xd0/0x210 mm/slub.c:2842 kmem_cache_alloc_node include/linux/slab.h:427 [inline] alloc_task_struct_node kernel/fork.c:171 [inline] dup_task_struct+0x4f/0x5a0 kernel/fork.c:871 copy_process+0x56e/0x3230 kernel/fork.c:1878 _do_fork+0x196/0x8d0 kernel/fork.c:2391 __do_sys_clone kernel/fork.c:2549 [inline] __se_sys_clone kernel/fork.c:2530 [inline] __x64_sys_clone+0x287/0x2f0 kernel/fork.c:2530 do_syscall_64+0xcb/0x1c0 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x5c/0xc1 Freed by task 155: save_stack mm/kasan/common.c:70 [inline] set_track mm/kasan/common.c:78 [inline] kasan_set_free_info mm/kasan/common.c:345 [inline] __kasan_slab_free+0x178/0x240 mm/kasan/common.c:487 slab_free_hook mm/slub.c:1455 [inline] slab_free_freelist_hook+0x80/0x150 mm/slub.c:1494 slab_free mm/slub.c:3080 [inline] kmem_cache_free+0xa9/0x1d0 mm/slub.c:3096 __rcu_reclaim kernel/rcu/rcu.h:222 [inline] rcu_do_batch+0x49e/0xa10 kernel/rcu/tree.c:2167 rcu_core+0x4ba/0xca0 kernel/rcu/tree.c:2387 __do_softirq+0x23e/0x643 kernel/softirq.c:292 The buggy address belongs to the object at ffff8881ca97bf00 which belongs to the cache task_struct of size 3904 The buggy address is located 56 bytes inside of 3904-byte region [ffff8881ca97bf00, ffff8881ca97ce40) The buggy address belongs to the page: page:ffffea00072a5e00 refcount:1 mapcount:0 mapping:ffff8881f5cec500 index:0xffff8881ca97af40 compound_mapcount: 0 flags: 0x8000000000010200(slab|head) raw: 8000000000010200 dead000000000100 dead000000000122 ffff8881f5cec500 raw: ffff8881ca97af40 0000000080080007 00000001ffffffff 0000000000000000 page dumped because: kasan: bad access detected page_owner tracks the page as allocated page last allocated via order 3, migratetype Unmovable, gfp_mask 0x1d20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_HARDWALL) set_page_owner include/linux/page_owner.h:31 [inline] post_alloc_hook mm/page_alloc.c:2165 [inline] prep_new_page+0x194/0x380 mm/page_alloc.c:2171 get_page_from_freelist+0x524/0x560 mm/page_alloc.c:3794 __alloc_pages_nodemask+0x372/0x860 mm/page_alloc.c:4891 alloc_slab_page+0x39/0x3e0 mm/slub.c:343 allocate_slab mm/slub.c:1683 [inline] new_slab+0x97/0x450 mm/slub.c:1749 new_slab_objects mm/slub.c:2505 [inline] ___slab_alloc+0x320/0x4a0 mm/slub.c:2667 __slab_alloc+0x5a/0x90 mm/slub.c:2707 slab_alloc_node mm/slub.c:2792 [inline] slab_alloc mm/slub.c:2837 [inline] kmem_cache_alloc+0x100/0x210 mm/slub.c:2842 kmem_cache_alloc_node include/linux/slab.h:427 [inline] alloc_task_struct_node kernel/fork.c:171 [inline] dup_task_struct+0x4f/0x5a0 kernel/fork.c:871 copy_process+0x56e/0x3230 kernel/fork.c:1878 _do_fork+0x196/0x8d0 kernel/fork.c:2391 __do_sys_clone kernel/fork.c:2549 [inline] __se_sys_clone kernel/fork.c:2530 [inline] __x64_sys_clone+0x287/0x2f0 kernel/fork.c:2530 do_syscall_64+0xcb/0x1c0 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x5c/0xc1 page last free stack trace: reset_page_owner include/linux/page_owner.h:24 [inline] free_pages_prepare mm/page_alloc.c:1176 [inline] __free_pages_ok+0x7fe/0x930 mm/page_alloc.c:1438 free_the_page mm/page_alloc.c:4953 [inline] __free_pages+0x8f/0x250 mm/page_alloc.c:4959 free_thread_stack kernel/fork.c:299 [inline] release_task_stack kernel/fork.c:439 [inline] put_task_stack+0x21a/0x270 kernel/fork.c:450 finish_task_switch+0x248/0x560 kernel/sched/core.c:3476 context_switch kernel/sched/core.c:3608 [inline] __schedule+0x98e/0x1050 kernel/sched/core.c:4305 preempt_schedule_common+0x93/0xe0 kernel/sched/core.c:4454 preempt_schedule+0xd9/0xe0 kernel/sched/core.c:4479 ___preempt_schedule+0x16/0x20 arch/x86/entry/thunk_64.S:50 try_to_wake_up+0xab2/0x1190 kernel/sched/core.c:2861 wake_up_process kernel/sched/core.c:2879 [inline] wake_up_q+0xa3/0x100 kernel/sched/core.c:502 futex_wake+0x600/0x820 kernel/futex.c:1724 do_futex+0x13f4/0x19c0 kernel/futex.c:3893 __do_sys_futex kernel/futex.c:3949 [inline] __se_sys_futex+0x34c/0x470 kernel/futex.c:3917 do_syscall_64+0xcb/0x1c0 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x5c/0xc1 Memory state around the buggy address: ffff8881ca97be00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8881ca97be80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff8881ca97bf00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff8881ca97bf80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8881ca97c000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================