================================================================== BUG: KASAN: use-after-free in css_task_iter_advance+0x49b/0x540 kernel/cgroup/cgroup.c:4507 Read of size 4 at addr ffff8880a83081dc by task syz-executor.1/16689 CPU: 0 PID: 16689 Comm: syz-executor.1 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 __cgroup_procs_start.isra.0+0x32f/0x400 kernel/cgroup/cgroup.c:4638 cgroup_threads_start+0x23/0x30 kernel/cgroup/cgroup.c:4745 cgroup_seqfile_start+0xa4/0xd0 kernel/cgroup/cgroup.c:3752 kernfs_seq_start+0xdc/0x190 fs/kernfs/file.c:118 seq_read+0x2a7/0x1110 fs/seq_file.c:224 kernfs_fop_read+0xed/0x560 fs/kernfs/file.c:252 do_loop_readv_writev fs/read_write.c:714 [inline] do_loop_readv_writev fs/read_write.c:701 [inline] do_iter_read+0x4a4/0x660 fs/read_write.c:935 vfs_readv+0xf0/0x160 fs/read_write.c:997 do_readv+0x15b/0x330 fs/read_write.c:1034 __do_sys_readv fs/read_write.c:1125 [inline] __se_sys_readv fs/read_write.c:1122 [inline] __x64_sys_readv+0x75/0xb0 fs/read_write.c:1122 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:00007fab28ad2c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000013 RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000459279 RDX: 000000000000018f RSI: 00000000200002c0 RDI: 0000000000000004 RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007fab28ad36d4 R13: 00000000004c6392 R14: 00000000004db1c0 R15: 00000000ffffffff Allocated by task 16651: 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_kmalloc+0x9/0x10 mm/kasan/common.c:503 __do_kmalloc_node mm/slab.c:3614 [inline] __kmalloc_node+0x4e/0x70 mm/slab.c:3621 kmalloc_node include/linux/slab.h:590 [inline] kvmalloc_node+0x68/0x100 mm/util.c:506 kvmalloc include/linux/mm.h:637 [inline] kvzalloc include/linux/mm.h:645 [inline] bucket_table_alloc+0x90/0x480 lib/rhashtable.c:178 rhashtable_init+0x3f4/0x7b0 lib/rhashtable.c:1057 br_mdb_hash_init+0x20/0x30 net/bridge/br_multicast.c:2448 br_dev_init+0x116/0x340 net/bridge/br_device.c:131 register_netdevice+0x2fd/0xff0 net/core/dev.c:8635 register_netdev+0x30/0x50 net/core/dev.c:8823 br_add_bridge+0xa4/0x100 net/bridge/br_if.c:456 br_ioctl_deviceless_stub+0x71a/0x7b0 net/bridge/br_ioctl.c:374 sock_ioctl+0x44b/0x780 net/socket.c:1141 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:509 [inline] do_vfs_ioctl+0xdb6/0x13e0 fs/ioctl.c:696 ksys_ioctl+0xab/0xd0 fs/ioctl.c:713 __do_sys_ioctl fs/ioctl.c:720 [inline] __se_sys_ioctl fs/ioctl.c:718 [inline] __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:718 do_syscall_64+0xfd/0x680 arch/x86/entry/common.c:301 entry_SYSCALL_64_after_hwframe+0x49/0xbe Freed by task 16664: 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] kfree+0x106/0x2a0 mm/slab.c:3753 kvfree+0x61/0x70 mm/util.c:535 bucket_table_free+0x69/0x150 lib/rhashtable.c:108 rhashtable_free_and_destroy+0x162/0x8b0 lib/rhashtable.c:1155 rhashtable_destroy+0x1a/0x20 lib/rhashtable.c:1166 br_mdb_hash_fini+0x19/0x20 net/bridge/br_multicast.c:2453 br_dev_uninit+0x36/0x80 net/bridge/br_device.c:165 rollback_registered_many+0xab8/0xfc0 net/core/dev.c:8192 unregister_netdevice_many.part.0+0x1b/0x1f0 net/core/dev.c:9286 unregister_netdevice_many+0x3b/0x50 net/core/dev.c:9285 rtnl_delete_link+0xda/0x130 net/core/rtnetlink.c:2805 rtnl_dellink+0x35a/0x970 net/core/rtnetlink.c:2860 rtnetlink_rcv_msg+0x463/0xb00 net/core/rtnetlink.c:5214 netlink_rcv_skb+0x177/0x450 net/netlink/af_netlink.c:2482 rtnetlink_rcv+0x1d/0x30 net/core/rtnetlink.c:5232 netlink_unicast_kernel net/netlink/af_netlink.c:1307 [inline] netlink_unicast+0x531/0x710 net/netlink/af_netlink.c:1333 netlink_sendmsg+0x8a5/0xd60 net/netlink/af_netlink.c:1922 sock_sendmsg_nosec net/socket.c:646 [inline] sock_sendmsg+0xd7/0x130 net/socket.c:665 ___sys_sendmsg+0x803/0x920 net/socket.c:2287 __sys_sendmsg+0x105/0x1d0 net/socket.c:2332 __do_sys_sendmsg net/socket.c:2341 [inline] __se_sys_sendmsg net/socket.c:2339 [inline] __x64_sys_sendmsg+0x78/0xb0 net/socket.c:2339 do_syscall_64+0xfd/0x680 arch/x86/entry/common.c:301 entry_SYSCALL_64_after_hwframe+0x49/0xbe The buggy address belongs to the object at ffff8880a8308000 which belongs to the cache kmalloc-1k of size 1024 The buggy address is located 476 bytes inside of 1024-byte region [ffff8880a8308000, ffff8880a8308400) The buggy address belongs to the page: page:ffffea0002a0c200 refcount:1 mapcount:0 mapping:ffff8880aa400ac0 index:0xffff8880a8308d80 compound_mapcount: 0 flags: 0x1fffc0000010200(slab|head) raw: 01fffc0000010200 ffffea000279c708 ffffea000284eb88 ffff8880aa400ac0 raw: ffff8880a8308d80 ffff8880a8308000 0000000100000006 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff8880a8308080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8880a8308100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff8880a8308180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff8880a8308200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8880a8308280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================