Hello, syzbot found the following crash on: HEAD commit: 7ae77150 Merge tag 'powerpc-5.8-1' of git://git.kernel.org.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=12ad963e100000 kernel config: https://syzkaller.appspot.com/x/.config?x=d195fe572fb15312 dashboard link: https://syzkaller.appspot.com/bug?extid=3b66039191adbe4be590 compiler: gcc (GCC) 9.0.0 20181231 (experimental) Unfortunately, I don't have any reproducer for this crash yet. IMPORTANT: if you fix the bug, please add the following tag to the commit: Reported-by: syzbot+3b66039191adbe4be590@xxxxxxxxxxxxxxxxxxxxxxxxx ================================================================== BUG: KASAN: use-after-free in cgroup_path_ns_locked+0xd0/0x110 kernel/cgroup/cgroup.c:2227 Read of size 8 at addr ffff888093fc42b8 by task syz-executor.5/12988 CPU: 0 PID: 12988 Comm: syz-executor.5 Not tainted 5.7.0-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+0x188/0x20d lib/dump_stack.c:118 print_address_description.constprop.0.cold+0xd3/0x413 mm/kasan/report.c:383 __kasan_report mm/kasan/report.c:513 [inline] kasan_report.cold+0x1f/0x37 mm/kasan/report.c:530 cgroup_path_ns_locked+0xd0/0x110 kernel/cgroup/cgroup.c:2227 cgroup_path_ns+0x43/0x70 kernel/cgroup/cgroup.c:2240 proc_cpuset_show+0x2ad/0xad0 kernel/cgroup/cpuset.c:3599 proc_single_show+0x116/0x1e0 fs/proc/base.c:766 seq_read+0x432/0xfd0 fs/seq_file.c:208 do_loop_readv_writev fs/read_write.c:715 [inline] do_loop_readv_writev fs/read_write.c:702 [inline] do_iter_read+0x483/0x650 fs/read_write.c:936 vfs_readv+0xf0/0x160 fs/read_write.c:1054 do_preadv+0x1bc/0x270 fs/read_write.c:1146 do_syscall_64+0xf6/0x7d0 arch/x86/entry/common.c:295 entry_SYSCALL_64_after_hwframe+0x49/0xb3 RIP: 0033:0x45ca69 Code: 0d b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 db b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007f11f653cc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000127 RAX: ffffffffffffffda RBX: 00000000004fb040 RCX: 000000000045ca69 RDX: 000000000000011c RSI: 00000000200017c0 RDI: 0000000000000004 RBP: 000000000078bfa0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 0000000000000879 R14: 00000000004cb670 R15: 00007f11f653d6d4 Allocated by task 1: save_stack+0x1b/0x40 mm/kasan/common.c:48 set_track mm/kasan/common.c:56 [inline] __kasan_kmalloc mm/kasan/common.c:494 [inline] __kasan_kmalloc.constprop.0+0xbf/0xd0 mm/kasan/common.c:467 kmem_cache_alloc_trace+0x153/0x7d0 mm/slab.c:3551 kmalloc include/linux/slab.h:555 [inline] kzalloc include/linux/slab.h:669 [inline] cgroup1_root_to_use kernel/cgroup/cgroup-v1.c:1183 [inline] cgroup1_get_tree+0xcfd/0x13b6 kernel/cgroup/cgroup-v1.c:1207 vfs_get_tree+0x89/0x2f0 fs/super.c:1547 do_new_mount fs/namespace.c:2874 [inline] do_mount+0x1306/0x1b40 fs/namespace.c:3199 __do_sys_mount fs/namespace.c:3409 [inline] __se_sys_mount fs/namespace.c:3386 [inline] __x64_sys_mount+0x18f/0x230 fs/namespace.c:3386 do_syscall_64+0xf6/0x7d0 arch/x86/entry/common.c:295 entry_SYSCALL_64_after_hwframe+0x49/0xb3 Freed by task 22806: save_stack+0x1b/0x40 mm/kasan/common.c:48 set_track mm/kasan/common.c:56 [inline] kasan_set_free_info mm/kasan/common.c:316 [inline] __kasan_slab_free+0xf7/0x140 mm/kasan/common.c:455 __cache_free mm/slab.c:3426 [inline] kfree+0x109/0x2b0 mm/slab.c:3757 cgroup_free_root kernel/cgroup/cgroup.c:1311 [inline] cgroup_destroy_root kernel/cgroup/cgroup.c:1353 [inline] css_free_rwork_fn+0x8e6/0xce0 kernel/cgroup/cgroup.c:4980 process_one_work+0x965/0x16a0 kernel/workqueue.c:2268 worker_thread+0x96/0xe20 kernel/workqueue.c:2414 kthread+0x388/0x470 kernel/kthread.c:268 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:351 The buggy address belongs to the object at ffff888093fc4000 which belongs to the cache kmalloc-8k of size 8192 The buggy address is located 696 bytes inside of 8192-byte region [ffff888093fc4000, ffff888093fc6000) The buggy address belongs to the page: page:ffffea00024ff100 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 head:ffffea00024ff100 order:2 compound_mapcount:0 compound_pincount:0 flags: 0xfffe0000010200(slab|head) raw: 00fffe0000010200 ffffea00024fe408 ffffea00024ffb08 ffff8880aa0021c0 raw: 0000000000000000 ffff888093fc4000 0000000100000001 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff888093fc4180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888093fc4200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff888093fc4280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff888093fc4300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888093fc4380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ================================================================== --- This bug is generated by a bot. 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