Date:   Sun, 16 Sep 2018 04:03:03 -0700
From:   syzbot <syzbot+2e406a9ac75bb71d4b7a@...kaller.appspotmail.com>
To:     davem@...emloft.net, kuznet@....inr.ac.ru,
        linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
        syzkaller-bugs@...glegroups.com, yoshfuji@...ux-ipv6.org
Subject: KMSAN: uninit-value in ip_rcv_core

Hello,

syzbot found the following crash on:

HEAD commit:    42a037ca8d9d kmsan: update README.md to reference LLVM r34..
git tree:       https://github.com/google/kmsan.git/master
console output: https://syzkaller.appspot.com/x/log.txt?x=1089adea400000
kernel config:  https://syzkaller.appspot.com/x/.config?x=3431f03869413153
dashboard link: https://syzkaller.appspot.com/bug?extid=2e406a9ac75bb71d4b7a
compiler:       clang version 8.0.0 (trunk 339414)
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=12d6d421400000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=13fdeb7a400000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+2e406a9ac75bb71d4b7a@...kaller.appspotmail.com

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: KMSAN: uninit-value in ip_rcv_core+0xabd/0x1160 net/ipv4/ip_input.c:464
CPU: 1 PID: 4270 Comm: syz-executor158 Not tainted 4.19.0-rc1+ #42
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
Call Trace:
  <IRQ>
  __dump_stack lib/dump_stack.c:77 [inline]
  dump_stack+0x14b/0x190 lib/dump_stack.c:113
  kmsan_report+0x183/0x2b0 mm/kmsan/kmsan.c:956
  __msan_warning+0x70/0xc0 mm/kmsan/kmsan_instr.c:645
  ip_rcv_core+0xabd/0x1160 net/ipv4/ip_input.c:464
  ip_rcv+0xbb/0x6d0 net/ipv4/ip_input.c:521
  __netif_receive_skb_one_core net/core/dev.c:4892 [inline]
  __netif_receive_skb net/core/dev.c:5002 [inline]
  process_backlog+0x752/0x10b0 net/core/dev.c:5808
  napi_poll net/core/dev.c:6228 [inline]
  net_rx_action+0x723/0x19d0 net/core/dev.c:6294
  __do_softirq+0x562/0x948 kernel/softirq.c:292
  do_softirq_own_stack+0x49/0x80 arch/x86/entry/entry_64.S:1055
  </IRQ>
  do_softirq kernel/softirq.c:336 [inline]
  __local_bh_enable_ip+0x119/0x150 kernel/softirq.c:189
  local_bh_enable+0x36/0x40 include/linux/bottom_half.h:32
  rcu_read_unlock_bh include/linux/rcupdate.h:723 [inline]
  __dev_queue_xmit+0x35a8/0x3ab0 net/core/dev.c:3830
  dev_queue_xmit+0x4b/0x60 net/core/dev.c:3836
  packet_snd net/packet/af_packet.c:2925 [inline]
  packet_sendmsg+0x80ff/0x8c60 net/packet/af_packet.c:2950
  sock_sendmsg_nosec net/socket.c:621 [inline]
  sock_sendmsg net/socket.c:631 [inline]
  ___sys_sendmsg+0xe70/0x1290 net/socket.c:2114
  __sys_sendmsg net/socket.c:2152 [inline]
  __do_sys_sendmsg net/socket.c:2161 [inline]
  __se_sys_sendmsg+0x2a3/0x3d0 net/socket.c:2159
  __x64_sys_sendmsg+0x4a/0x70 net/socket.c:2159
  do_syscall_64+0xb8/0x100 arch/x86/entry/common.c:291
  entry_SYSCALL_64_after_hwframe+0x63/0xe7
RIP: 0033:0x441149
Code: 18 89 d0 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 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 db 0a fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007ffebf721a18 EFLAGS: 00000286 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 0000000000441149
RDX: 0000000000000000 RSI: 0000000020000240 RDI: 0000000000000003
RBP: 00000000006cc018 R08: 0000000000000100 R09: 0000000000000100
R10: 0000000000000100 R11: 0000000000000286 R12: 00000000004020b0
R13: 0000000000402140 R14: 0000000000000000 R15: 0000000000000000

Uninit was stored to memory at:
  kmsan_save_stack_with_flags mm/kmsan/kmsan.c:256 [inline]
  kmsan_save_stack mm/kmsan/kmsan.c:271 [inline]
  kmsan_internal_chain_origin+0x128/0x210 mm/kmsan/kmsan.c:573
  __msan_chain_origin+0x69/0xc0 mm/kmsan/kmsan_instr.c:482
  iptunnel_xmit+0xa3c/0xd50 net/ipv4/ip_tunnel_core.c:85
  ip_tunnel_xmit+0x33e1/0x3750 net/ipv4/ip_tunnel.c:778
  __gre_xmit net/ipv4/ip_gre.c:449 [inline]
  ipgre_xmit+0xdcf/0xeb0 net/ipv4/ip_gre.c:703
  __netdev_start_xmit include/linux/netdevice.h:4287 [inline]
  netdev_start_xmit include/linux/netdevice.h:4296 [inline]
  xmit_one net/core/dev.c:3217 [inline]
  dev_hard_start_xmit+0x5df/0xc20 net/core/dev.c:3233
  __dev_queue_xmit+0x2f35/0x3ab0 net/core/dev.c:3803
  dev_queue_xmit+0x4b/0x60 net/core/dev.c:3836
  packet_snd net/packet/af_packet.c:2925 [inline]
  packet_sendmsg+0x80ff/0x8c60 net/packet/af_packet.c:2950
  sock_sendmsg_nosec net/socket.c:621 [inline]
  sock_sendmsg net/socket.c:631 [inline]
  ___sys_sendmsg+0xe70/0x1290 net/socket.c:2114
  __sys_sendmsg net/socket.c:2152 [inline]
  __do_sys_sendmsg net/socket.c:2161 [inline]
  __se_sys_sendmsg+0x2a3/0x3d0 net/socket.c:2159
  __x64_sys_sendmsg+0x4a/0x70 net/socket.c:2159
  do_syscall_64+0xb8/0x100 arch/x86/entry/common.c:291
  entry_SYSCALL_64_after_hwframe+0x63/0xe7

Uninit was created at:
  kmsan_save_stack_with_flags mm/kmsan/kmsan.c:256 [inline]
  kmsan_internal_poison_shadow+0xb8/0x1b0 mm/kmsan/kmsan.c:181
  kmsan_kmalloc+0x98/0x100 mm/kmsan/kmsan_hooks.c:91
  kmsan_slab_alloc+0x10/0x20 mm/kmsan/kmsan_hooks.c:100
  slab_post_alloc_hook mm/slab.h:446 [inline]
  slab_alloc_node mm/slub.c:2719 [inline]
  __kmalloc_node_track_caller+0x9e7/0x1160 mm/slub.c:4352
  __kmalloc_reserve net/core/skbuff.c:138 [inline]
  __alloc_skb+0x2f5/0x9e0 net/core/skbuff.c:206
  alloc_skb include/linux/skbuff.h:996 [inline]
  alloc_skb_with_frags+0x1d0/0xac0 net/core/skbuff.c:5276
  sock_alloc_send_pskb+0xb47/0x1170 net/core/sock.c:2082
  packet_alloc_skb net/packet/af_packet.c:2779 [inline]
  packet_snd net/packet/af_packet.c:2870 [inline]
  packet_sendmsg+0x6599/0x8c60 net/packet/af_packet.c:2950
  sock_sendmsg_nosec net/socket.c:621 [inline]
  sock_sendmsg net/socket.c:631 [inline]
  ___sys_sendmsg+0xe70/0x1290 net/socket.c:2114
  __sys_sendmsg net/socket.c:2152 [inline]
  __do_sys_sendmsg net/socket.c:2161 [inline]
  __se_sys_sendmsg+0x2a3/0x3d0 net/socket.c:2159
  __x64_sys_sendmsg+0x4a/0x70 net/socket.c:2159
  do_syscall_64+0xb8/0x100 arch/x86/entry/common.c:291
  entry_SYSCALL_64_after_hwframe+0x63/0xe7
==================================================================


---
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