================================================================== BUG: KASAN: use-after-free in dec_rlimit_ucounts+0x127/0x130 kernel/ucount.c:284 Read of size 8 at addr ffff88807f940608 by task kworker/0:3/7915 CPU: 0 PID: 7915 Comm: kworker/0:3 Not tainted 5.15.0-next-20211110-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: events free_ipc Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106 print_address_description.constprop.0.cold+0x8d/0x320 mm/kasan/report.c:247 __kasan_report mm/kasan/report.c:433 [inline] kasan_report.cold+0x83/0xdf mm/kasan/report.c:450 dec_rlimit_ucounts+0x127/0x130 kernel/ucount.c:284 mqueue_evict_inode+0x7f0/0xc90 ipc/mqueue.c:537 evict+0x2ed/0x6b0 fs/inode.c:592 iput_final fs/inode.c:1672 [inline] iput.part.0+0x539/0x850 fs/inode.c:1698 iput+0x58/0x70 fs/inode.c:1688 dentry_unlink_inode+0x2b1/0x460 fs/dcache.c:376 __dentry_kill+0x3c0/0x640 fs/dcache.c:582 shrink_dentry_list+0x128/0x490 fs/dcache.c:1176 shrink_dcache_parent+0x1fe/0x3c0 fs/dcache.c:1603 do_one_tree fs/dcache.c:1657 [inline] shrink_dcache_for_umount+0x71/0x330 fs/dcache.c:1674 generic_shutdown_super+0x68/0x400 fs/super.c:447 kill_anon_super fs/super.c:1059 [inline] kill_litter_super+0x6e/0xa0 fs/super.c:1068 deactivate_locked_super+0x94/0x160 fs/super.c:335 deactivate_super+0xad/0xd0 fs/super.c:366 cleanup_mnt+0x3a2/0x540 fs/namespace.c:1137 mntput_no_expire+0x908/0xcd0 fs/namespace.c:1223 mntput fs/namespace.c:1233 [inline] kern_unmount fs/namespace.c:4369 [inline] kern_unmount+0xb5/0xe0 fs/namespace.c:4363 free_ipc_ns ipc/namespace.c:123 [inline] free_ipc+0xf0/0x200 ipc/namespace.c:141 process_one_work+0x9b2/0x1690 kernel/workqueue.c:2298 worker_thread+0x658/0x11f0 kernel/workqueue.c:2445 kthread+0x405/0x4f0 kernel/kthread.c:327 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 Allocated by task 31632: kasan_save_stack+0x1e/0x50 mm/kasan/common.c:38 kasan_set_track mm/kasan/common.c:46 [inline] set_alloc_info mm/kasan/common.c:434 [inline] __kasan_slab_alloc+0x90/0xc0 mm/kasan/common.c:467 kasan_slab_alloc include/linux/kasan.h:259 [inline] slab_post_alloc_hook mm/slab.h:519 [inline] slab_alloc_node mm/slub.c:3234 [inline] slab_alloc mm/slub.c:3242 [inline] kmem_cache_alloc+0x202/0x3a0 mm/slub.c:3247 kmem_cache_zalloc include/linux/slab.h:714 [inline] create_user_ns+0x1ac/0xdd0 kernel/user_namespace.c:105 copy_creds+0x6f0/0xb60 kernel/cred.c:370 copy_process+0x1443/0x75a0 kernel/fork.c:2114 kernel_clone+0xe7/0xab0 kernel/fork.c:2633 __do_sys_clone+0xc8/0x110 kernel/fork.c:2750 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae Last potentially related work creation: kasan_save_stack+0x1e/0x50 mm/kasan/common.c:38 __kasan_record_aux_stack+0xf5/0x120 mm/kasan/generic.c:348 insert_work+0x48/0x370 kernel/workqueue.c:1354 __queue_work+0x5ca/0xf30 kernel/workqueue.c:1520 queue_work_on+0xee/0x110 kernel/workqueue.c:1547 put_user_ns include/linux/user_namespace.h:156 [inline] put_cred_rcu+0x35e/0x520 kernel/cred.c:125 rcu_do_batch kernel/rcu/tree.c:2506 [inline] rcu_core+0x7ab/0x1470 kernel/rcu/tree.c:2741 __do_softirq+0x29b/0x9c2 kernel/softirq.c:558 The buggy address belongs to the object at ffff88807f940388 which belongs to the cache user_namespace of size 776 The buggy address is located 640 bytes inside of 776-byte region [ffff88807f940388, ffff88807f940690) The buggy address belongs to the page: page:ffffea0001fe5000 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x7f940 head:ffffea0001fe5000 order:2 compound_mapcount:0 compound_pincount:0 flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff) raw: 00fff00000010200 0000000000000000 dead000000000122 ffff8880155c8280 raw: 0000000000000000 0000000080120012 00000001ffffffff 0000000000000000 page dumped because: kasan: bad access detected page_owner tracks the page as allocated page last allocated via order 2, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 9163, ts 190898874041, free_ts 190898491377 prep_new_page mm/page_alloc.c:2418 [inline] get_page_from_freelist+0xa72/0x2f50 mm/page_alloc.c:4149 __alloc_pages+0x1b2/0x500 mm/page_alloc.c:5369 alloc_pages+0x1a7/0x300 mm/mempolicy.c:2191 alloc_slab_page mm/slub.c:1793 [inline] allocate_slab mm/slub.c:1930 [inline] new_slab+0x32d/0x4a0 mm/slub.c:1993 ___slab_alloc+0x918/0xfe0 mm/slub.c:3022 __slab_alloc.constprop.0+0x4d/0xa0 mm/slub.c:3109 slab_alloc_node mm/slub.c:3200 [inline] slab_alloc mm/slub.c:3242 [inline] kmem_cache_alloc+0x35c/0x3a0 mm/slub.c:3247 kmem_cache_zalloc include/linux/slab.h:714 [inline] create_user_ns+0x1ac/0xdd0 kernel/user_namespace.c:105 copy_creds+0x6f0/0xb60 kernel/cred.c:370 copy_process+0x1443/0x75a0 kernel/fork.c:2114 kernel_clone+0xe7/0xab0 kernel/fork.c:2633 __do_sys_clone+0xc8/0x110 kernel/fork.c:2750 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae page last free stack trace: reset_page_owner include/linux/page_owner.h:24 [inline] free_pages_prepare mm/page_alloc.c:1338 [inline] free_pcp_prepare+0x374/0x870 mm/page_alloc.c:1389 free_unref_page_prepare mm/page_alloc.c:3309 [inline] free_unref_page+0x19/0x690 mm/page_alloc.c:3388 qlink_free mm/kasan/quarantine.c:146 [inline] qlist_free_all+0x5a/0xc0 mm/kasan/quarantine.c:165 kasan_quarantine_reduce+0x180/0x200 mm/kasan/quarantine.c:272 __kasan_slab_alloc+0xa2/0xc0 mm/kasan/common.c:444 kasan_slab_alloc include/linux/kasan.h:259 [inline] slab_post_alloc_hook mm/slab.h:519 [inline] slab_alloc_node mm/slub.c:3234 [inline] kmem_cache_alloc_node+0x255/0x3f0 mm/slub.c:3270 alloc_task_struct_node kernel/fork.c:170 [inline] dup_task_struct kernel/fork.c:933 [inline] copy_process+0x5c4/0x75a0 kernel/fork.c:2074 kernel_clone+0xe7/0xab0 kernel/fork.c:2633 __do_sys_clone+0xc8/0x110 kernel/fork.c:2750 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae Memory state around the buggy address: ffff88807f940500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88807f940580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff88807f940600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff88807f940680: fb fb fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff88807f940700: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ==================================================================