KMSAN: uninit-value in ebt_stp_mt_check

From: syzbot <syzbot+5c06e318fc558cc27823@syzkaller.appspotmail.com>
To: bridge@lists.linux-foundation.org, coreteam@netfilter.org,
	davem@davemloft.net, fw@strlen.de, kadlec@blackhole.kfki.hu,
	linux-kernel@vger.kernel.org, netdev@vger.kernel.org,
	netfilter-devel@vger.kernel.org, pablo@netfilter.org,
	stephen@networkplumber.org, syzkaller-bugs@googlegroups.com
Subject: KMSAN: uninit-value in ebt_stp_mt_check
Date: Mon, 23 Apr 2018 01:23:01 -0700	[thread overview]
Message-ID: <0000000000000734c0056a7fbf3b@google.com> (raw)

Hello,

syzbot hit the following crash on  
https://github.com/google/kmsan.git/master commit
a7f95e9c8a95e9fbb388c3999b61a17667cd3bbe (Sat Apr 21 13:50:22 2018 +0000)
kmsan: disable assembly checksums
syzbot dashboard link:  
https://syzkaller.appspot.com/bug?extid=5c06e318fc558cc27823

So far this crash happened 3 times on  
https://github.com/google/kmsan.git/master.
C reproducer: https://syzkaller.appspot.com/x/repro.c?id=5411555638247424
syzkaller reproducer:  
https://syzkaller.appspot.com/x/repro.syz?id=6309829995921408
Raw console output:  
https://syzkaller.appspot.com/x/log.txt?id=4546610964987904
Kernel config: https://syzkaller.appspot.com/x/.config?id=328654897048964367
compiler: clang version 7.0.0 (trunk 329391)

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Reported-by: syzbot+5c06e318fc558cc27823@syzkaller.appspotmail.com
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==================================================================
BUG: KMSAN: uninit-value in ebt_stp_mt_check+0x248/0x410  
net/bridge/netfilter/ebt_stp.c:164
CPU: 0 PID: 4520 Comm: syzkaller565841 Not tainted 4.16.0+ #85
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
Call Trace:
  __dump_stack lib/dump_stack.c:17 [inline]
  dump_stack+0x185/0x1d0 lib/dump_stack.c:53
  kmsan_report+0x142/0x240 mm/kmsan/kmsan.c:1067
  __msan_warning_32+0x6c/0xb0 mm/kmsan/kmsan_instr.c:683
  ebt_stp_mt_check+0x248/0x410 net/bridge/netfilter/ebt_stp.c:164
  xt_check_match+0x1449/0x1660 net/netfilter/x_tables.c:499
  ebt_check_match net/bridge/netfilter/ebtables.c:374 [inline]
  ebt_check_entry net/bridge/netfilter/ebtables.c:704 [inline]
  translate_table+0x3ffd/0x5e10 net/bridge/netfilter/ebtables.c:945
  do_replace_finish+0x1258/0x2ea0 net/bridge/netfilter/ebtables.c:1002
  do_replace+0x707/0x770 net/bridge/netfilter/ebtables.c:1141
  do_ebt_set_ctl+0x2ab/0x3c0 net/bridge/netfilter/ebtables.c:1518
  nf_sockopt net/netfilter/nf_sockopt.c:106 [inline]
  nf_setsockopt+0x476/0x4d0 net/netfilter/nf_sockopt.c:115
  ip_setsockopt+0x24b/0x2b0 net/ipv4/ip_sockglue.c:1261
  dccp_setsockopt+0x1c3/0x1f0 net/dccp/proto.c:576
  sock_common_setsockopt+0x136/0x170 net/core/sock.c:2975
  SYSC_setsockopt+0x4b8/0x570 net/socket.c:1849
  SyS_setsockopt+0x76/0xa0 net/socket.c:1828
  do_syscall_64+0x309/0x430 arch/x86/entry/common.c:287
  entry_SYSCALL_64_after_hwframe+0x3d/0xa2
RIP: 0033:0x445d39
RSP: 002b:00007efff4e14da8 EFLAGS: 00000246 ORIG_RAX: 0000000000000036
RAX: ffffffffffffffda RBX: 00000000006dac24 RCX: 0000000000445d39
RDX: 0000000000000080 RSI: 0000000000000000 RDI: 0000000000000003
RBP: 0000000000000000 R08: 0000000000000358 R09: 0000000000000000
R10: 00000000200008c0 R11: 0000000000000246 R12: 00000000006dac20
R13: 006567646972625f R14: 6f745f3168746576 R15: 0000000000000002

Local variable description: ----mtpar.i@translate_table
Variable was created at:
  translate_table+0xb9/0x5e10 net/bridge/netfilter/ebtables.c:833
  do_replace_finish+0x1258/0x2ea0 net/bridge/netfilter/ebtables.c:1002
==================================================================

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