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BUG: KASAN: use-after-free in atomic_read include/asm-generic/atomic-instrumented.h:26 [inline]
BUG: KASAN: use-after-free in refcount_inc_not_zero_checked+0x72/0x160 lib/refcount.c:123
Read of size 4 at addr ffff88809860a1c8 by task syz-executor.3/21644

CPU: 0 PID: 21644 Comm: syz-executor.3 Not tainted 5.2.0-rc2+ #1
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+0x113/0x167 lib/dump_stack.c:113
 print_address_description.cold.5+0x9/0x1ff mm/kasan/report.c:188
 __kasan_report.cold.6+0x1b/0x39 mm/kasan/report.c:317
 kasan_report+0x12/0x20 mm/kasan/common.c:614
 check_memory_region_inline mm/kasan/generic.c:185 [inline]
 check_memory_region+0x13e/0x1b0 mm/kasan/generic.c:191
 kasan_check_read+0x11/0x20 mm/kasan/common.c:94
 atomic_read include/asm-generic/atomic-instrumented.h:26 [inline]
 refcount_inc_not_zero_checked+0x72/0x160 lib/refcount.c:123
 refcount_inc_checked+0x9/0x30 lib/refcount.c:156
 css_task_iter_next+0xc5/0x140 kernel/cgroup/cgroup.c:4534
 pidlist_array_load+0x148/0x8d0 kernel/cgroup/cgroup-v1.c:373
 cgroup_pidlist_start+0x333/0x530 kernel/cgroup/cgroup-v1.c:442
 cgroup_seqfile_start+0xa7/0x100 kernel/cgroup/cgroup.c:3738
 kernfs_seq_start+0xcc/0x170 fs/kernfs/file.c:118
 seq_read+0x253/0x1000 fs/seq_file.c:224
 kernfs_fop_read+0xcc/0x4f0 fs/kernfs/file.c:252
 do_loop_readv_writev fs/read_write.c:714 [inline]
 do_iter_read+0x366/0x560 fs/read_write.c:935
 vfs_readv+0xc9/0x130 fs/read_write.c:997
 do_preadv+0x158/0x230 fs/read_write.c:1089
 __do_sys_preadv fs/read_write.c:1139 [inline]
 __se_sys_preadv fs/read_write.c:1134 [inline]
 __x64_sys_preadv+0x95/0xf0 fs/read_write.c:1134
 do_syscall_64+0xd0/0x530 arch/x86/entry/common.c:301
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x459279
Code: fd 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 cb b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f60b0f29c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000127
RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 0000000000459279
RDX: 0000000000000001 RSI: 0000000020000100 RDI: 0000000000000005
RBP: 000000000075c060 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f60b0f2a6d4
R13: 00000000004c614c R14: 00000000004da9a8 R15: 00000000ffffffff

Allocated by task 21314:
 save_stack+0x21/0x90 mm/kasan/common.c:71
 set_track mm/kasan/common.c:79 [inline]
 __kasan_kmalloc.constprop.8+0xc7/0xd0 mm/kasan/common.c:489
 kasan_kmalloc+0x9/0x10 mm/kasan/common.c:503
 kmem_cache_alloc_trace+0x154/0x740 mm/slab.c:3555
 kmalloc include/linux/slab.h:547 [inline]
 kzalloc include/linux/slab.h:742 [inline]
 find_css_set+0x5c5/0x1b00 kernel/cgroup/cgroup.c:1202
 cgroup_migrate_prepare_dst+0xf2/0x6e0 kernel/cgroup/cgroup.c:2648
 cgroup_attach_task+0x2df/0x630 kernel/cgroup/cgroup.c:2758
 cgroup_attach_task_all+0xaf/0x120 kernel/cgroup/cgroup-v1.c:76
 vhost_attach_cgroups_work+0x39/0x90 drivers/vhost/vhost.c:472
 vhost_worker+0x251/0x4a0 drivers/vhost/vhost.c:362
 kthread+0x324/0x3e0 kernel/kthread.c:255
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352

Freed by task 16:
 save_stack+0x21/0x90 mm/kasan/common.c:71
 set_track mm/kasan/common.c:79 [inline]
 __kasan_slab_free+0x102/0x150 mm/kasan/common.c:451
 kasan_slab_free+0xe/0x10 mm/kasan/common.c:459
 __cache_free mm/slab.c:3432 [inline]
 kfree+0xcf/0x220 mm/slab.c:3755
 __rcu_reclaim kernel/rcu/rcu.h:215 [inline]
 rcu_do_batch kernel/rcu/tree.c:2092 [inline]
 invoke_rcu_callbacks kernel/rcu/tree.c:2310 [inline]
 rcu_core+0xc8e/0x1430 kernel/rcu/tree.c:2291
 __do_softirq+0x260/0x958 kernel/softirq.c:293

The buggy address belongs to the object at ffff88809860a000
 which belongs to the cache kmalloc-1k of size 1024
The buggy address is located 456 bytes inside of
 1024-byte region [ffff88809860a000, ffff88809860a400)
The buggy address belongs to the page:
page:ffffea0002618280 refcount:1 mapcount:0 mapping:ffff8880aa400ac0 index:0xffff88809860ad80 compound_mapcount: 0
flags: 0x1fffc0000010200(slab|head)
raw: 01fffc0000010200 ffffea000247d908 ffffea0002352c88 ffff8880aa400ac0
raw: ffff88809860ad80 ffff88809860a000 0000000100000004 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88809860a080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88809860a100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88809860a180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                              ^
 ffff88809860a200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88809860a280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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