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BUG: KASAN: use-after-free in css_task_iter_advance+0x49b/0x540 kernel/cgroup/cgroup.c:4507
Read of size 4 at addr ffff8880a74a991c by task syz-executor.5/18352

CPU: 0 PID: 18352 Comm: syz-executor.5 Not tainted 5.2.0-rc3-next-20190607 #11
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+0x172/0x1f0 lib/dump_stack.c:113
 print_address_description.cold+0xd4/0x306 mm/kasan/report.c:351
 __kasan_report.cold+0x1b/0x36 mm/kasan/report.c:482
 kasan_report+0x12/0x20 mm/kasan/common.c:614
 __asan_report_load4_noabort+0x14/0x20 mm/kasan/generic_report.c:131
 css_task_iter_advance+0x49b/0x540 kernel/cgroup/cgroup.c:4507
 css_task_iter_start+0x18b/0x230 kernel/cgroup/cgroup.c:4543
 mem_cgroup_scan_tasks+0xaf/0x180 mm/memcontrol.c:1167
 select_bad_process mm/oom_kill.c:374 [inline]
 out_of_memory mm/oom_kill.c:1088 [inline]
 out_of_memory+0x6b2/0x1280 mm/oom_kill.c:1035
 mem_cgroup_out_of_memory+0x1ca/0x230 mm/memcontrol.c:1573
 mem_cgroup_oom mm/memcontrol.c:1905 [inline]
 try_charge+0xfbe/0x1480 mm/memcontrol.c:2468
 mem_cgroup_try_charge+0x24d/0x5e0 mm/memcontrol.c:6073
 mem_cgroup_try_charge_delay+0x1f/0xa0 mm/memcontrol.c:6088
 do_anonymous_page mm/memory.c:3036 [inline]
 handle_pte_fault mm/memory.c:3890 [inline]
 __handle_mm_fault+0x1e1a/0x3eb0 mm/memory.c:4016
 handle_mm_fault+0x3b7/0xa90 mm/memory.c:4053
 do_user_addr_fault arch/x86/mm/fault.c:1455 [inline]
 __do_page_fault+0x5ef/0xda0 arch/x86/mm/fault.c:1521
 do_page_fault+0x71/0x57d arch/x86/mm/fault.c:1552
 page_fault+0x1e/0x30 arch/x86/entry/entry_64.S:1156
RIP: 0033:0x410bbf
Code: 0f 84 c8 02 00 00 48 83 bd 78 ff ff ff 00 0f 84 f9 04 00 00 48 8b 95 68 ff ff ff 44 89 95 38 ff ff ff 4c 8d ac 10 00 f7 ff ff <49> 89 85 90 06 00 00 49 8d 85 10 03 00 00 49 89 95 98 06 00 00 41
RSP: 002b:00007fffb3110570 EFLAGS: 00010206
RAX: 00007fe59e341000 RBX: 0000000000020000 RCX: 00000000004592ca
RDX: 0000000000021000 RSI: 0000000000021000 RDI: 0000000000000000
RBP: 00007fffb3110650 R08: ffffffffffffffff R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fffb3110740
R13: 00007fe59e361700 R14: 0000000000000001 R15: 000000000075bfcc

Allocated by task 2:
 save_stack+0x23/0x90 mm/kasan/common.c:71
 set_track mm/kasan/common.c:79 [inline]
 __kasan_kmalloc mm/kasan/common.c:489 [inline]
 __kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:462
 kasan_slab_alloc+0xf/0x20 mm/kasan/common.c:497
 slab_post_alloc_hook mm/slab.h:444 [inline]
 slab_alloc mm/slab.c:3320 [inline]
 kmem_cache_alloc+0x11a/0x6f0 mm/slab.c:3482
 kmem_cache_zalloc include/linux/slab.h:732 [inline]
 copy_signal kernel/fork.c:1547 [inline]
 copy_process.part.0+0x2224/0x6720 kernel/fork.c:2054
 copy_process kernel/fork.c:1828 [inline]
 _do_fork+0x25d/0xfe0 kernel/fork.c:2394
 kernel_thread+0x34/0x40 kernel/fork.c:2453
 create_kthread kernel/kthread.c:278 [inline]
 kthreadd+0x52a/0x740 kernel/kthread.c:596
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352

Freed by task 12712:
 save_stack+0x23/0x90 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:3426 [inline]
 kmem_cache_free+0x86/0x320 mm/slab.c:3692
 free_signal_struct kernel/fork.c:710 [inline]
 put_signal_struct kernel/fork.c:716 [inline]
 __put_task_struct+0x2e4/0x4e0 kernel/fork.c:730
 put_task_struct include/linux/sched/task.h:99 [inline]
 delayed_put_task_struct+0x1ea/0x340 kernel/exit.c:182
 __rcu_reclaim kernel/rcu/rcu.h:222 [inline]
 rcu_do_batch kernel/rcu/tree.c:2092 [inline]
 invoke_rcu_callbacks kernel/rcu/tree.c:2310 [inline]
 rcu_core+0xba5/0x1500 kernel/rcu/tree.c:2291
 __do_softirq+0x25c/0x94c kernel/softirq.c:293

The buggy address belongs to the object at ffff8880a74a9400
 which belongs to the cache signal_cache of size 1328
The buggy address is located 1308 bytes inside of
 1328-byte region [ffff8880a74a9400, ffff8880a74a9930)
The buggy address belongs to the page:
page:ffffea00029d2a00 refcount:1 mapcount:0 mapping:ffff8880aa587600 index:0xffff8880a74a9400 compound_mapcount: 0
flags: 0x1fffc0000010200(slab|head)
raw: 01fffc0000010200 ffffea00028c0608 ffffea00027a2d88 ffff8880aa587600
raw: ffff8880a74a9400 ffff8880a74a82c0 0000000100000004 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8880a74a9800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8880a74a9880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff8880a74a9900: fb fb fb fb fb fb fc fc fc fc fc fc fc fc fc fc
                            ^
 ffff8880a74a9980: fc fc fc fc fc fc fc fc 00 00 00 00 00 00 00 00
 ffff8880a74a9a00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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