Subject: KASAN: use-after-free Read in neigh_mark_dead

From: syzbot <[email-masked]>
Date: Sun, 09 Dec 2018 21:41:05 -0800

Hello,

syzbot found the following crash on:

HEAD commit:    a60956ed72f7 net: dsa: Make dsa_master_set_mtu() static
git tree:       net-next
console output: https://syzkaller.appspot.com/x/log.txt?x=14df67eb400000
kernel config:  https://syzkaller.appspot.com/x/.config?x=28ecefa8a6e10719
dashboard link: https://syzkaller.appspot.com/bug?extid=35e87b87c00f386b041f
compiler:       gcc (GCC) 8.0.1 20180413 (experimental)
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1444565d400000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=123832db400000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: [email-masked]

IPv6: ADDRCONF(NETDEV_UP): veth1: link is not ready
IPv6: ADDRCONF(NETDEV_CHANGE): veth1: link becomes ready
IPv6: ADDRCONF(NETDEV_CHANGE): veth0: link becomes ready
8021q: adding VLAN 0 to HW filter on device team0
==================================================================
BUG: KASAN: use-after-free in __list_del_entry_valid+0xf1/0x100  
lib/list_debug.c:51
Read of size 8 at addr ffff8881bb7394b0 by task ip/7510

CPU: 0 PID: 7510 Comm: ip Not tainted 4.20.0-rc4+ #335
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+0x244/0x39d lib/dump_stack.c:113
  print_address_description.cold.7+0x9/0x1ff mm/kasan/report.c:256
  kasan_report_error mm/kasan/report.c:354 [inline]
  kasan_report.cold.8+0x242/0x309 mm/kasan/report.c:412
  __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433
  __list_del_entry_valid+0xf1/0x100 lib/list_debug.c:51
  __list_del_entry include/linux/list.h:117 [inline]
  list_del_init include/linux/list.h:159 [inline]
  neigh_mark_dead+0x13b/0x410 net/core/neighbour.c:125
  neigh_flush_dev+0x3a1/0x960 net/core/neighbour.c:290
  neigh_changeaddr+0x31/0x40 net/core/neighbour.c:319
  ndisc_netdev_event+0xe6/0x5b0 net/ipv6/ndisc.c:1770
  notifier_call_chain+0x17e/0x380 kernel/notifier.c:93
  __raw_notifier_call_chain kernel/notifier.c:394 [inline]
  raw_notifier_call_chain+0x2d/0x40 kernel/notifier.c:401
  call_netdevice_notifiers_info+0x3f/0x90 net/core/dev.c:1737
  call_netdevice_notifiers_extack net/core/dev.c:1749 [inline]
  call_netdevice_notifiers net/core/dev.c:1763 [inline]
  dev_set_mac_address+0x293/0x3b0 net/core/dev.c:7775
  do_setlink+0x7c7/0x3f30 net/core/rtnetlink.c:2447
  __rtnl_newlink+0xcde/0x19e0 net/core/rtnetlink.c:3115
  rtnl_newlink+0x6b/0xa0 net/core/rtnetlink.c:3240
  rtnetlink_rcv_msg+0x46a/0xc20 net/core/rtnetlink.c:4966
  netlink_rcv_skb+0x172/0x440 net/netlink/af_netlink.c:2477
  rtnetlink_rcv+0x1c/0x20 net/core/rtnetlink.c:4984
  netlink_unicast_kernel net/netlink/af_netlink.c:1310 [inline]
  netlink_unicast+0x5a5/0x760 net/netlink/af_netlink.c:1336
  netlink_sendmsg+0xa18/0xfc0 net/netlink/af_netlink.c:1917
  sock_sendmsg_nosec net/socket.c:621 [inline]
  sock_sendmsg+0xd5/0x120 net/socket.c:631
  ___sys_sendmsg+0x7fd/0x930 net/socket.c:2116
  __sys_sendmsg+0x11d/0x280 net/socket.c:2154
  __do_sys_sendmsg net/socket.c:2163 [inline]
  __se_sys_sendmsg net/socket.c:2161 [inline]
  __x64_sys_sendmsg+0x78/0xb0 net/socket.c:2161
  do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
  entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x7f1baeb6e320
Code: 02 48 83 c8 ff eb 8d 48 8b 05 14 7b 2a 00 f7 da 64 89 10 48 83 c8 ff  
eb c9 90 83 3d d5 d2 2a 00 00 75 10 b8 2e 00 00 00 0f 05 <48> 3d 01 f0 ff  
ff 73 31 c3 48 83 ec 08 e8 5e ba 00 00 48 89 04 24
RSP: 002b:00007fff37bc5c58 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007fff37bc9d50 RCX: 00007f1baeb6e320
RDX: 0000000000000000 RSI: 00007fff37bc5c90 RDI: 0000000000000003
RBP: 00007fff37bc5c90 R08: 0000000000000000 R09: 000000000000000e
R10: 0000000000000000 R11: 0000000000000246 R12: 000000005c0d8897
R13: 0000000000000000 R14: 00000000006395c0 R15: 00007fff37bca530

Allocated by task 22:
  save_stack+0x43/0xd0 mm/kasan/kasan.c:448
  set_track mm/kasan/kasan.c:460 [inline]
  kasan_kmalloc+0xc7/0xe0 mm/kasan/kasan.c:553
  __do_kmalloc mm/slab.c:3722 [inline]
  __kmalloc+0x15b/0x760 mm/slab.c:3731
  kmalloc include/linux/slab.h:551 [inline]
  kzalloc include/linux/slab.h:741 [inline]
  neigh_alloc net/core/neighbour.c:375 [inline]
  ___neigh_create+0x13fc/0x2600 net/core/neighbour.c:553
  __neigh_create+0x30/0x40 net/core/neighbour.c:640
  ip6_finish_output2+0xa59/0x27a0 net/ipv6/ip6_output.c:117
  ip6_finish_output+0x58c/0xc60 net/ipv6/ip6_output.c:154
  NF_HOOK_COND include/linux/netfilter.h:278 [inline]
  ip6_output+0x232/0x9d0 net/ipv6/ip6_output.c:171
  dst_output include/net/dst.h:444 [inline]
  NF_HOOK include/linux/netfilter.h:289 [inline]
  ndisc_send_skb+0x1005/0x1560 net/ipv6/ndisc.c:491
  ndisc_send_ns+0x3c6/0x8e0 net/ipv6/ndisc.c:633
  addrconf_dad_work+0xbf2/0x1310 net/ipv6/addrconf.c:4081
  process_one_work+0xc90/0x1c40 kernel/workqueue.c:2153
  worker_thread+0x17f/0x1390 kernel/workqueue.c:2296
  kthread+0x35a/0x440 kernel/kthread.c:246
  ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:352

Freed by task 9:
  save_stack+0x43/0xd0 mm/kasan/kasan.c:448
  set_track mm/kasan/kasan.c:460 [inline]
  __kasan_slab_free+0x102/0x150 mm/kasan/kasan.c:521
  kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528
  __cache_free mm/slab.c:3498 [inline]
  kfree+0xcf/0x230 mm/slab.c:3817
  __rcu_reclaim kernel/rcu/rcu.h:233 [inline]
  rcu_do_batch kernel/rcu/tree.c:2437 [inline]
  invoke_rcu_callbacks kernel/rcu/tree.c:2716 [inline]
  rcu_process_callbacks+0x1140/0x1ac0 kernel/rcu/tree.c:2697
  __do_softirq+0x308/0xb7e kernel/softirq.c:292

The buggy address belongs to the object at ffff8881bb739240
  which belongs to the cache kmalloc-1k of size 1024
The buggy address is located 624 bytes inside of
  1024-byte region [ffff8881bb739240, ffff8881bb739640)
The buggy address belongs to the page:
page:ffffea0006edce00 count:1 mapcount:0 mapping:ffff8881da800ac0 index:0x0  
compound_mapcount: 0
flags: 0x2fffc0000010200(slab|head)
raw: 02fffc0000010200 ffffea0006eb2d88 ffffea0006eea708 ffff8881da800ac0
raw: 0000000000000000 ffff8881bb738040 0000000100000007 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
  ffff8881bb739380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
  ffff8881bb739400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> ffff8881bb739480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                      ^
  ffff8881bb739500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
  ffff8881bb739580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

---
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