Subject: BUG: corrupted list in ___neigh_create

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

Hello,

syzbot found the following crash on:

HEAD commit:    97ef7b4c5501 ip: silence udp zerocopy smatch false positive
git tree:       net-next
console output: https://syzkaller.appspot.com/x/log.txt?x=13f4592b400000
kernel config:  https://syzkaller.appspot.com/x/.config?x=28ecefa8a6e10719
dashboard link: https://syzkaller.appspot.com/bug?extid=b354d1fb59091ea73c37
compiler:       gcc (GCC) 8.0.1 20180413 (experimental)
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1442c925400000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=17778d6d400000

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

list_add corruption. prev->next should be next (ffffffff89fd0da0), but was  
ffff8881d7bf42b0. (prev=ffff8881d4465db0).
------------[ cut here ]------------
kernel BUG at lib/list_debug.c:28!
invalid opcode: 0000 [#1] PREEMPT SMP KASAN
CPU: 0 PID: 6257 Comm: syz-executor648 Not tainted 4.20.0-rc4+ #334
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
RIP: 0010:__list_add_valid.cold.2+0x23/0x2a lib/list_debug.c:26
Code: e8 90 fd d1 fd 0f 0b 48 89 d9 48 c7 c7 a0 d8 60 88 e8 7f fd d1 fd 0f  
0b 48 89 f1 48 c7 c7 20 d9 60 88 48 89 de e8 6b fd d1 fd <0f> 0b 90 90 90  
90 90 55 48 89 e5 41 57 41 56 49 be 00 00 00 00 00
RSP: 0018:ffff8881dae06cf0 EFLAGS: 00010282
RAX: 0000000000000075 RBX: ffffffff89fd0da0 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff8165eae5 RDI: 0000000000000005
RBP: ffff8881dae06d08 R08: ffff8881bcdbe000 R09: ffffed103b5c5020
R10: ffffed103b5c5020 R11: ffff8881dae28107 R12: ffff8881ce059030
R13: ffff8881ce058dc0 R14: ffffffff89fd0b60 R15: ffffffff89fd0df0
FS:  0000000000000000(0000) GS:ffff8881dae00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000000042de80 CR3: 00000001bd45f000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
  <IRQ>
  __list_add include/linux/list.h:60 [inline]
  list_add_tail include/linux/list.h:93 [inline]
  neigh_alloc net/core/neighbour.c:395 [inline]
  ___neigh_create+0x14b7/0x2600 net/core/neighbour.c:553
cgroup: fork rejected by pids controller in /syz2
cgroup: fork rejected by pids controller in /syz5
  __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_rs+0x134/0x6e0 net/ipv6/ndisc.c:685
  addrconf_rs_timer+0x314/0x690 net/ipv6/addrconf.c:3840
  call_timer_fn+0x272/0x920 kernel/time/timer.c:1326
  expire_timers kernel/time/timer.c:1363 [inline]
  __run_timers+0x7e5/0xc70 kernel/time/timer.c:1682
cgroup: fork rejected by pids controller in /syz0
  run_timer_softirq+0x52/0xb0 kernel/time/timer.c:1695
cgroup: fork rejected by pids controller in /syz4
  __do_softirq+0x308/0xb7e kernel/softirq.c:292
cgroup: fork rejected by pids controller in /syz3
  invoke_softirq kernel/softirq.c:373 [inline]
  irq_exit+0x17f/0x1c0 kernel/softirq.c:413
  exiting_irq arch/x86/include/asm/apic.h:536 [inline]
  smp_apic_timer_interrupt+0x1cb/0x760 arch/x86/kernel/apic/apic.c:1061
  apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:804
  </IRQ>
RIP: 0010:arch_atomic_add_negative arch/x86/include/asm/atomic.h:154  
[inline]
RIP: 0010:atomic_add_negative include/asm-generic/atomic-instrumented.h:398  
[inline]
RIP: 0010:page_remove_file_rmap mm/rmap.c:1235 [inline]
RIP: 0010:page_remove_rmap+0x934/0x1a30 mm/rmap.c:1300
Code: 32 6a c7 ff 45 85 ff 0f 85 45 fb ff ff e9 0d f9 ff ff e8 0f 69 c7 ff  
48 8d 7b 30 be 04 00 00 00 e8 11 d6 0a 00 f0 83 43 30 ff <41> 0f 98 c4 31  
ff 44 89 e6 e8 be 69 c7 ff 45 84 e4 0f 84 3e ff ff
RSP: 0018:ffff8881c1786918 EFLAGS: 00000213 ORIG_RAX: ffffffffffffff13
RAX: fffff94000d8c6b7 RBX: ffffea0006c63580 RCX: ffffffff81b821ef
RDX: 0000000000000001 RSI: 0000000000000004 RDI: ffffea0006c635b0
RBP: ffff8881c1786c88 R08: fffff94000d8c6b7 R09: fffff94000d8c6b6
R10: fffff94000d8c6b6 R11: ffffea0006c635b3 R12: 0000000000000000
R13: ffff8881c1786c60 R14: ffffea0006c63588 R15: 0000000000000000
  zap_pte_range mm/memory.c:1091 [inline]
  zap_pmd_range mm/memory.c:1193 [inline]
  zap_pud_range mm/memory.c:1222 [inline]
  zap_p4d_range mm/memory.c:1243 [inline]
  unmap_page_range+0x11c7/0x2930 mm/memory.c:1264
  unmap_single_vma+0x19b/0x310 mm/memory.c:1309
  unmap_vmas+0x125/0x200 mm/memory.c:1339
  exit_mmap+0x2be/0x590 mm/mmap.c:3145
  __mmput kernel/fork.c:1045 [inline]
  mmput+0x247/0x610 kernel/fork.c:1066
  exit_mm kernel/exit.c:545 [inline]
  do_exit+0xe74/0x26d0 kernel/exit.c:854
  do_group_exit+0x177/0x440 kernel/exit.c:970
  get_signal+0x8b0/0x1980 kernel/signal.c:2517
  do_signal+0x9c/0x21c0 arch/x86/kernel/signal.c:816
  exit_to_usermode_loop+0x2e5/0x380 arch/x86/entry/common.c:162
  prepare_exit_to_usermode arch/x86/entry/common.c:197 [inline]
  syscall_return_slowpath arch/x86/entry/common.c:268 [inline]
  do_syscall_64+0x6be/0x820 arch/x86/entry/common.c:293
  entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x4480f9
Code: Bad RIP value.
RSP: 002b:00007ffccd7c26e8 EFLAGS: 00000202 ORIG_RAX: 00000000000000ca
RAX: fffffffffffffdfc RBX: 000000000003f97b RCX: 00000000004480f9
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00000000006dec2c
RBP: 0000000000000004 R08: 0000000000000000 R09: 0000000000000000
R10: 00007ffccd7c26f0 R11: 0000000000000202 R12: 00000000000003e8
R13: 00000000006dec2c R14: 00000000006dec20 R15: 000000000000002d
Modules linked in:
---[ end trace 32027e846ce348df ]---
RIP: 0010:__list_add_valid.cold.2+0x23/0x2a lib/list_debug.c:26
Code: e8 90 fd d1 fd 0f 0b 48 89 d9 48 c7 c7 a0 d8 60 88 e8 7f fd d1 fd 0f  
0b 48 89 f1 48 c7 c7 20 d9 60 88 48 89 de e8 6b fd d1 fd <0f> 0b 90 90 90  
90 90 55 48 89 e5 41 57 41 56 49 be 00 00 00 00 00
RSP: 0018:ffff8881dae06cf0 EFLAGS: 00010282
RAX: 0000000000000075 RBX: ffffffff89fd0da0 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff8165eae5 RDI: 0000000000000005
RBP: ffff8881dae06d08 R08: ffff8881bcdbe000 R09: ffffed103b5c5020
R10: ffffed103b5c5020 R11: ffff8881dae28107 R12: ffff8881ce059030
R13: ffff8881ce058dc0 R14: ffffffff89fd0b60 R15: ffffffff89fd0df0
FS:  0000000000000000(0000) GS:ffff8881dae00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000004480cf CR3: 00000001bd45f000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400

---
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