================================================================== BUG: KASAN: use-after-free in css_task_iter_advance+0x49b/0x540 kernel/cgroup/cgroup.c:4507 Read of size 4 at addr ffff888097a981dc by task syz-executor.2/21896 CPU: 0 PID: 21896 Comm: syz-executor.2 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 pidlist_array_load+0x181/0xa80 kernel/cgroup/cgroup-v1.c:372 cgroup_pidlist_start+0x37e/0x4c0 kernel/cgroup/cgroup-v1.c:442 cgroup_seqfile_start+0xa4/0xd0 kernel/cgroup/cgroup.c:3752 kernfs_seq_start+0xdc/0x190 fs/kernfs/file.c:118 traverse fs/seq_file.c:108 [inline] traverse+0x165/0x740 fs/seq_file.c:91 seq_read+0x8dd/0x1110 fs/seq_file.c:188 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 kernel_readv fs/splice.c:359 [inline] default_file_splice_read+0x475/0x890 fs/splice.c:414 do_splice_to+0x127/0x180 fs/splice.c:877 splice_direct_to_actor+0x2d2/0x970 fs/splice.c:954 do_splice_direct+0x1da/0x2a0 fs/splice.c:1063 do_sendfile+0x597/0xd00 fs/read_write.c:1464 __do_sys_sendfile64 fs/read_write.c:1519 [inline] __se_sys_sendfile64 fs/read_write.c:1511 [inline] __x64_sys_sendfile64+0x15a/0x220 fs/read_write.c:1511 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:00007fb737250c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000028 RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 0000000000459279 RDX: 0000000020000040 RSI: 0000000000000004 RDI: 0000000000000004 RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000008000000006 R11: 0000000000000246 R12: 00007fb7372516d4 R13: 00000000004c6835 R14: 00000000004db7a8 R15: 00000000ffffffff Allocated by task 20024: 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_track_caller+0x4e/0x70 mm/slab.c:3628 __kmalloc_reserve.isra.0+0x40/0xf0 net/core/skbuff.c:139 __alloc_skb+0x10b/0x5e0 net/core/skbuff.c:207 alloc_skb_fclone include/linux/skbuff.h:1104 [inline] tipc_buf_acquire+0x2f/0x100 net/tipc/msg.c:66 tipc_msg_build+0x113/0x1240 net/tipc/msg.c:277 __tipc_sendmsg+0x9d8/0x18c0 net/tipc/socket.c:1393 tipc_sendmsg+0x53/0x80 net/tipc/socket.c:1291 sock_sendmsg_nosec net/socket.c:646 [inline] sock_sendmsg+0xd7/0x130 net/socket.c:665 ___sys_sendmsg+0x3e2/0x920 net/socket.c:2287 __sys_sendmmsg+0x1bf/0x4d0 net/socket.c:2389 __do_sys_sendmmsg net/socket.c:2418 [inline] __se_sys_sendmmsg net/socket.c:2415 [inline] __x64_sys_sendmmsg+0x9d/0x100 net/socket.c:2415 do_syscall_64+0xfd/0x680 arch/x86/entry/common.c:301 entry_SYSCALL_64_after_hwframe+0x49/0xbe Freed by task 20023: 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 skb_free_head+0x93/0xb0 net/core/skbuff.c:589 skb_release_data+0x42d/0x7c0 net/core/skbuff.c:609 skb_release_all+0x4d/0x60 net/core/skbuff.c:663 __kfree_skb net/core/skbuff.c:677 [inline] kfree_skb net/core/skbuff.c:695 [inline] kfree_skb+0xe8/0x390 net/core/skbuff.c:689 tipc_msg_reverse+0x66f/0x860 net/tipc/msg.c:554 tipc_sk_respond+0x287/0x8d0 net/tipc/socket.c:249 __tipc_shutdown+0x743/0xcb0 net/tipc/socket.c:532 tipc_release+0xcb/0x1830 net/tipc/socket.c:582 __sock_release+0xce/0x2a0 net/socket.c:601 sock_close+0x1b/0x30 net/socket.c:1273 __fput+0x2ff/0x890 fs/file_table.c:280 ____fput+0x16/0x20 fs/file_table.c:313 task_work_run+0x145/0x1c0 kernel/task_work.c:113 tracehook_notify_resume include/linux/tracehook.h:188 [inline] exit_to_usermode_loop+0x273/0x2c0 arch/x86/entry/common.c:168 prepare_exit_to_usermode arch/x86/entry/common.c:199 [inline] syscall_return_slowpath arch/x86/entry/common.c:279 [inline] do_syscall_64+0x58e/0x680 arch/x86/entry/common.c:304 entry_SYSCALL_64_after_hwframe+0x49/0xbe The buggy address belongs to the object at ffff888097a98000 which belongs to the cache kmalloc-1k of size 1024 The buggy address is located 476 bytes inside of 1024-byte region [ffff888097a98000, ffff888097a98400) The buggy address belongs to the page: page:ffffea00025ea600 refcount:1 mapcount:0 mapping:ffff8880aa400ac0 index:0xffff888097a99680 compound_mapcount: 0 flags: 0x1fffc0000010200(slab|head) raw: 01fffc0000010200 ffffea00026c0f08 ffffea0002800b88 ffff8880aa400ac0 raw: ffff888097a99680 ffff888097a98000 0000000100000003 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff888097a98080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888097a98100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff888097a98180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff888097a98200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888097a98280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb 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