linux-kernel - KMSAN: uninit-value in IP6_ECN

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Message-ID: <000000000000336563057653b9aa@google.com>
Date:   Thu, 20 Sep 2018 13:54:05 -0700
From:   syzbot <syzbot+bf7e6250c7ce248f3ec9@...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 IP6_ECN_decapsulate

Hello,

syzbot found the following crash on:

HEAD commit:    88e0e95b30f1 kmsan: add a newline before "Uninit was creat..
git tree:       https://github.com/google/kmsan.git/master
console output: https://syzkaller.appspot.com/x/log.txt?x=146dfccf800000
kernel config:  https://syzkaller.appspot.com/x/.config?x=848e40757852af3e
dashboard link: https://syzkaller.appspot.com/bug?extid=bf7e6250c7ce248f3ec9
compiler:       clang version 7.0.0 (trunk 334104)
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=177a9ce4400000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=14f68bd8400000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+bf7e6250c7ce248f3ec9@...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 INET_ECN_decapsulate include/net/inet_ecn.h:189  
[inline]
BUG: KMSAN: uninit-value in IP6_ECN_decapsulate+0x421/0x970  
include/net/inet_ecn.h:234
CPU: 0 PID: 4515 Comm: syz-executor162 Not tainted 4.17.0+ #8
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+0x185/0x1d0 lib/dump_stack.c:113
  kmsan_report+0x188/0x2a0 mm/kmsan/kmsan.c:1122
  __msan_warning_32+0x70/0xc0 mm/kmsan/kmsan_instr.c:620
  INET_ECN_decapsulate include/net/inet_ecn.h:189 [inline]
  IP6_ECN_decapsulate+0x421/0x970 include/net/inet_ecn.h:234
  ip6ip6_dscp_ecn_decapsulate+0x1e0/0x250 net/ipv6/ip6_tunnel.c:719
  __ip6_tnl_rcv+0xff9/0x1a10 net/ipv6/ip6_tunnel.c:829
  ip6_tnl_rcv+0xe6/0x110 net/ipv6/ip6_tunnel.c:868
  gre_rcv+0x1661/0x1a90 net/ipv6/ip6_gre.c:534
  ip6_input_finish+0x1353/0x2260 net/ipv6/ip6_input.c:284
  NF_HOOK include/linux/netfilter.h:288 [inline]
  ip6_input+0x294/0x320 net/ipv6/ip6_input.c:327
  dst_input include/net/dst.h:450 [inline]
  ip6_rcv_finish+0x498/0x6e0 net/ipv6/ip6_input.c:71
  NF_HOOK include/linux/netfilter.h:288 [inline]
  ipv6_rcv+0x1d6b/0x2360 net/ipv6/ip6_input.c:208
  __netif_receive_skb_core+0x47f3/0x4aa0 net/core/dev.c:4592
  __netif_receive_skb net/core/dev.c:4657 [inline]
  process_backlog+0x62d/0xe20 net/core/dev.c:5337
  napi_poll net/core/dev.c:5735 [inline]
  net_rx_action+0x766/0x1a80 net/core/dev.c:5801
  __do_softirq+0x592/0x979 kernel/softirq.c:285
  do_softirq_own_stack+0x2a/0x40 arch/x86/entry/entry_64.S:1046
  </IRQ>
  do_softirq kernel/softirq.c:329 [inline]
  __local_bh_enable_ip+0x114/0x140 kernel/softirq.c:182
  local_bh_enable+0x36/0x40 include/linux/bottom_half.h:32
  rcu_read_unlock_bh include/linux/rcupdate.h:728 [inline]
  ip6_finish_output2+0x1ce8/0x2100 net/ipv6/ip6_output.c:121
  ip6_finish_output+0xaf0/0xbb0 net/ipv6/ip6_output.c:154
  NF_HOOK_COND include/linux/netfilter.h:277 [inline]
  ip6_output+0x597/0x6c0 net/ipv6/ip6_output.c:171
  dst_output include/net/dst.h:444 [inline]
  ip6_local_out+0x164/0x1d0 net/ipv6/output_core.c:176
  ip6_send_skb net/ipv6/ip6_output.c:1703 [inline]
  ip6_push_pending_frames+0x218/0x4d0 net/ipv6/ip6_output.c:1723
  rawv6_push_pending_frames net/ipv6/raw.c:616 [inline]
  rawv6_sendmsg+0x4254/0x4fc0 net/ipv6/raw.c:935
  inet_sendmsg+0x3fc/0x760 net/ipv4/af_inet.c:798
  sock_sendmsg_nosec net/socket.c:629 [inline]
  sock_sendmsg net/socket.c:639 [inline]
  sock_write_iter+0x3bc/0x470 net/socket.c:908
  call_write_iter include/linux/fs.h:1784 [inline]
  new_sync_write fs/read_write.c:474 [inline]
  __vfs_write+0x808/0x9f0 fs/read_write.c:487
  vfs_write+0x467/0x8c0 fs/read_write.c:549
  ksys_write fs/read_write.c:598 [inline]
  __do_sys_write fs/read_write.c:610 [inline]
  __se_sys_write fs/read_write.c:607 [inline]
  __x64_sys_write+0x1bf/0x3e0 fs/read_write.c:607
  do_syscall_64+0x15b/0x230 arch/x86/entry/common.c:287
  entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x441199
RSP: 002b:00007fff83b55688 EFLAGS: 00000217 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000441199
RDX: 0000000000000004 RSI: 00000000200001c0 RDI: 0000000000000003
RBP: 00000000006cc018 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000217 R12: 00000000004020a0
R13: 0000000000402130 R14: 0000000000000000 R15: 0000000000000000

Uninit was created at:
  kmsan_save_stack_with_flags mm/kmsan/kmsan.c:279 [inline]
  kmsan_internal_poison_shadow+0xb8/0x1b0 mm/kmsan/kmsan.c:189
  kmsan_kmalloc+0x94/0x100 mm/kmsan/kmsan.c:315
  kmsan_slab_alloc+0x10/0x20 mm/kmsan/kmsan.c:322
  slab_post_alloc_hook mm/slab.h:446 [inline]
  slab_alloc_node mm/slub.c:2753 [inline]
  __kmalloc_node_track_caller+0xb35/0x11b0 mm/slub.c:4395
  __kmalloc_reserve net/core/skbuff.c:138 [inline]
  __alloc_skb+0x2cb/0x9e0 net/core/skbuff.c:206
  alloc_skb include/linux/skbuff.h:988 [inline]
  __ip6_append_data+0x364d/0x4fb0 net/ipv6/ip6_output.c:1434
  ip6_append_data+0x40e/0x6b0 net/ipv6/ip6_output.c:1597
  rawv6_sendmsg+0x2756/0x4fc0 net/ipv6/raw.c:928
  inet_sendmsg+0x3fc/0x760 net/ipv4/af_inet.c:798
  sock_sendmsg_nosec net/socket.c:629 [inline]
  sock_sendmsg net/socket.c:639 [inline]
  sock_write_iter+0x3bc/0x470 net/socket.c:908
  call_write_iter include/linux/fs.h:1784 [inline]
  new_sync_write fs/read_write.c:474 [inline]
  __vfs_write+0x808/0x9f0 fs/read_write.c:487
  vfs_write+0x467/0x8c0 fs/read_write.c:549
  ksys_write fs/read_write.c:598 [inline]
  __do_sys_write fs/read_write.c:610 [inline]
  __se_sys_write fs/read_write.c:607 [inline]
  __x64_sys_write+0x1bf/0x3e0 fs/read_write.c:607
  do_syscall_64+0x15b/0x230 arch/x86/entry/common.c:287
  entry_SYSCALL_64_after_hwframe+0x44/0xa9
==================================================================


---
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