================================================================== BUG: KASAN: use-after-free in css_task_iter_advance+0x49b/0x540 kernel/cgroup/cgroup.c:4507 Read of size 4 at addr ffff88808644a6a4 by task syz-executor.5/26270 CPU: 0 PID: 26270 Comm: syz-executor.5 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 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 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 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:1525 [inline] __se_sys_sendfile64 fs/read_write.c:1511 [inline] __x64_sys_sendfile64+0x1dd/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:00007f8dd5ec8c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000028 RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 0000000000459279 RDX: 0000000000000000 RSI: 0000000000000004 RDI: 0000000000000005 RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000010001 R11: 0000000000000246 R12: 00007f8dd5ec96d4 R13: 00000000004c65f3 R14: 00000000004db2a8 R15: 00000000ffffffff Allocated by task 8638: 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 mm/slab.c:3654 [inline] __kmalloc+0x15c/0x740 mm/slab.c:3663 kmalloc include/linux/slab.h:552 [inline] kzalloc include/linux/slab.h:742 [inline] neigh_alloc net/core/neighbour.c:402 [inline] ___neigh_create+0x122a/0x2350 net/core/neighbour.c:580 __neigh_create+0x2f/0x40 net/core/neighbour.c:674 ip6_finish_output2+0x94f/0x2550 net/ipv6/ip6_output.c:113 __ip6_finish_output+0x444/0xaa0 net/ipv6/ip6_output.c:142 ip6_finish_output+0x38/0x1f0 net/ipv6/ip6_output.c:152 NF_HOOK_COND include/linux/netfilter.h:294 [inline] ip6_output+0x235/0x7f0 net/ipv6/ip6_output.c:175 dst_output include/net/dst.h:433 [inline] NF_HOOK include/linux/netfilter.h:305 [inline] ndisc_send_skb+0xf29/0x14a0 net/ipv6/ndisc.c:504 ndisc_send_ns+0x3a9/0x850 net/ipv6/ndisc.c:646 rt6_probe_deferred+0xe3/0x1a0 net/ipv6/route.c:539 process_one_work+0x989/0x1790 kernel/workqueue.c:2269 worker_thread+0x98/0xe40 kernel/workqueue.c:2415 kthread+0x354/0x420 kernel/kthread.c:255 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352 Freed by task 26201: 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 __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+0xcc7/0x1500 kernel/rcu/tree.c:2291 __do_softirq+0x25c/0x94c kernel/softirq.c:293 The buggy address belongs to the object at ffff88808644a4c0 which belongs to the cache kmalloc-1k of size 1024 The buggy address is located 484 bytes inside of 1024-byte region [ffff88808644a4c0, ffff88808644a8c0) The buggy address belongs to the page: page:ffffea0002191280 refcount:1 mapcount:0 mapping:ffff8880aa400ac0 index:0xffff88808644a040 compound_mapcount: 0 flags: 0x1fffc0000010200(slab|head) raw: 01fffc0000010200 ffffea0001aa0c08 ffffea000263b108 ffff8880aa400ac0 raw: ffff88808644a040 ffff88808644a040 0000000100000004 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff88808644a580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88808644a600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff88808644a680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff88808644a700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88808644a780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================