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BUG: KASAN: slab-out-of-bounds in css_task_iter_advance+0x49b/0x540 kernel/cgroup/cgroup.c:4507
Read of size 4 at addr ffff8880a1798fe4 by task syz-executor.3/24182

CPU: 1 PID: 24182 Comm: syz-executor.3 Not tainted 5.2.0-rc3-next-20190604 #8
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:1166
 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:1492
 memory_max_write+0x256/0x3a0 mm/memcontrol.c:5623
 cgroup_file_write+0x241/0x790 kernel/cgroup/cgroup.c:3711
 kernfs_fop_write+0x2b8/0x480 fs/kernfs/file.c:316
 __vfs_write+0x8a/0x110 fs/read_write.c:494
 vfs_write+0x268/0x5d0 fs/read_write.c:558
 ksys_write+0x14f/0x290 fs/read_write.c:611
 __do_sys_write fs/read_write.c:623 [inline]
 __se_sys_write fs/read_write.c:620 [inline]
 __x64_sys_write+0x73/0xb0 fs/read_write.c:620
 do_syscall_64+0xfd/0x680 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:00007fcd981edc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000459279
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000005
RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fcd981ee6d4
R13: 00000000004c8eb1 R14: 00000000004dfb68 R15: 00000000ffffffff

Allocated by task 29235:
 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]
 __kernfs_new_node+0xf0/0x6c0 fs/kernfs/dir.c:632
 kernfs_new_node+0x96/0x120 fs/kernfs/dir.c:698
 kernfs_create_link+0xd7/0x250 fs/kernfs/symlink.c:40
 sysfs_do_create_link_sd.isra.0+0x90/0x140 fs/sysfs/symlink.c:44
 sysfs_do_create_link fs/sysfs/symlink.c:80 [inline]
 sysfs_create_link+0x65/0xc0 fs/sysfs/symlink.c:92
 device_add_class_symlinks drivers/base/core.c:1849 [inline]
 device_add+0x635/0x17a0 drivers/base/core.c:2077
 netdev_register_kobject+0x183/0x3b0 net/core/net-sysfs.c:1746
 register_netdevice+0x875/0xff0 net/core/dev.c:8705
 register_netdev+0x30/0x50 net/core/dev.c:8823
 ip6gre_init_net+0x3b1/0x5f0 net/ipv6/ip6_gre.c:1581
 ops_init+0xb3/0x410 net/core/net_namespace.c:130
 setup_net+0x2d3/0x740 net/core/net_namespace.c:316
 copy_net_ns+0x1df/0x340 net/core/net_namespace.c:439
 create_new_namespaces+0x400/0x7b0 kernel/nsproxy.c:107
 copy_namespaces+0x351/0x3f0 kernel/nsproxy.c:165
 copy_process.part.0+0x2d1e/0x6800 kernel/fork.c:2061
 copy_process kernel/fork.c:1826 [inline]
 _do_fork+0x25d/0xfe0 kernel/fork.c:2395
 __do_sys_clone kernel/fork.c:2502 [inline]
 __se_sys_clone kernel/fork.c:2496 [inline]
 __x64_sys_clone+0xbf/0x150 kernel/fork.c:2496
 do_syscall_64+0xfd/0x680 arch/x86/entry/common.c:301
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 0:
(stack is not available)

The buggy address belongs to the object at ffff8880a1798ee0
 which belongs to the cache kernfs_node_cache of size 160
The buggy address is located 100 bytes to the right of
 160-byte region [ffff8880a1798ee0, ffff8880a1798f80)
The buggy address belongs to the page:
page:ffffea000285e600 refcount:1 mapcount:0 mapping:ffff88821bc4b380 index:0xffff8880a1798fee
flags: 0x1fffc0000000200(slab)
raw: 01fffc0000000200 ffffea000298f2c8 ffffea0002908748 ffff88821bc4b380
raw: ffff8880a1798fee ffff8880a1798000 0000000100000012 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8880a1798e80: 00 00 00 00 fc fc fc fc fc fc fc fc 00 00 00 00
 ffff8880a1798f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff8880a1798f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                                                       ^
 ffff8880a1799000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8880a1799080: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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