Re: KMSAN: uninit-value in __sctp_v6_cmp_addr

[Alexander Potapenko]

On Wed, May 16, 2018 at 9:17 AM Xin Long <lucien.xin@xxxxxxxxx> wrote:

> On Wed, May 16, 2018 at 12:25 AM, syzbot
> <syzbot+85490c30c260afff22f2@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
> > Hello,
> >
> > syzbot found the following crash on:
> >
> > HEAD commit:    74ee2200b89f kmsan: bump .config.example to v4.17-rc3
> > git tree:       https://github.com/google/kmsan.git/master
> > console output: https://syzkaller.appspot.com/x/log.txt?x=169efb5b800000
> > kernel config:
https://syzkaller.appspot.com/x/.config?x=4ca1e57bafa8ab1f
> > dashboard link:
https://syzkaller.appspot.com/bug?extid=85490c30c260afff22f2
> > compiler:       clang version 7.0.0 (trunk 329391)
> > syzkaller repro:
https://syzkaller.appspot.com/x/repro.syz?x=157e9237800000
> > C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=10fe5de7800000
> >
> > IMPORTANT: if you fix the bug, please add the following tag to the
commit:
> > Reported-by: syzbot+85490c30c260afff22f2@xxxxxxxxxxxxxxxxxxxxxxxxx
> >
> > random: sshd: uninitialized urandom read (32 bytes read)
> > random: sshd: uninitialized urandom read (32 bytes read)
> > random: sshd: uninitialized urandom read (32 bytes read)
> > random: sshd: uninitialized urandom read (32 bytes read)
> > ==================================================================
> > BUG: KMSAN: uninit-value in __sctp_v6_cmp_addr+0x49a/0x850
> > net/sctp/ipv6.c:580
> > CPU: 0 PID: 4453 Comm: syz-executor325 Not tainted 4.17.0-rc3+ #88
> > 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+0x142/0x240 mm/kmsan/kmsan.c:1067
> >  __msan_warning_32+0x6c/0xb0 mm/kmsan/kmsan_instr.c:683
> >  __sctp_v6_cmp_addr+0x49a/0x850 net/sctp/ipv6.c:580
> Pls check if the testing kernel has this commit:
> commit d625329b06e46bd20baf9ee40847d11982569204
> Author: Xin Long <lucien.xin@xxxxxxxxx>
> Date:   Thu Apr 26 14:13:57 2018 +0800

>      sctp: handle two v4 addrs comparison in sctp_inet6_cmp_addr

It doesn't, because we were testing v4.17-rc3, and the patch is in
v4.17-rc4.
I'll update to -rc5 and test again.
> Thanks.
Thank you!
> >  sctp_inet6_cmp_addr+0x3dc/0x400 net/sctp/ipv6.c:898
> >  sctp_bind_addr_match+0x18b/0x2f0 net/sctp/bind_addr.c:330
> >  sctp_addrs_lookup_transport+0x904/0xa20 net/sctp/input.c:942
> >  __sctp_lookup_association net/sctp/input.c:985 [inline]
> >  __sctp_rcv_lookup net/sctp/input.c:1249 [inline]
> >  sctp_rcv+0x15e6/0x4d30 net/sctp/input.c:170
> >  ip_local_deliver_finish+0x874/0xec0 net/ipv4/ip_input.c:215
> >  NF_HOOK include/linux/netfilter.h:288 [inline]
> >  ip_local_deliver+0x43c/0x4e0 net/ipv4/ip_input.c:256
> >  dst_input include/net/dst.h:450 [inline]
> >  ip_rcv_finish+0xa36/0x1d00 net/ipv4/ip_input.c:396
> >  NF_HOOK include/linux/netfilter.h:288 [inline]
> >  ip_rcv+0x118f/0x16d0 net/ipv4/ip_input.c:492
> >  __netif_receive_skb_core+0x47df/0x4a90 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+0x7c1/0x1a70 net/core/dev.c:5801
> >  __do_softirq+0x56d/0x93d 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]
> >  ip_finish_output2+0x135a/0x1470 net/ipv4/ip_output.c:231
> >  ip_finish_output+0xcb2/0xff0 net/ipv4/ip_output.c:317
> >  NF_HOOK_COND include/linux/netfilter.h:277 [inline]
> >  ip_output+0x505/0x5d0 net/ipv4/ip_output.c:405
> >  dst_output include/net/dst.h:444 [inline]
> >  ip_local_out net/ipv4/ip_output.c:124 [inline]
> >  ip_queue_xmit+0x1a1e/0x1d10 net/ipv4/ip_output.c:504
> >  sctp_v4_xmit+0x188/0x210 net/sctp/protocol.c:983
> >  sctp_packet_transmit+0x3eaa/0x4350 net/sctp/output.c:650
> >  sctp_outq_flush+0x1a7a/0x6320 net/sctp/outqueue.c:1197
> >  sctp_outq_uncork+0xd2/0xf0 net/sctp/outqueue.c:776
> >  sctp_cmd_interpreter net/sctp/sm_sideeffect.c:1820 [inline]
> >  sctp_side_effects net/sctp/sm_sideeffect.c:1220 [inline]
> >  sctp_do_sm+0x8707/0x8d20 net/sctp/sm_sideeffect.c:1191
> >  sctp_primitive_REQUESTHEARTBEAT+0x175/0x1a0 net/sctp/primitive.c:200
> >  sctp_apply_peer_addr_params+0x207/0x1670 net/sctp/socket.c:2487
> >  sctp_setsockopt_peer_addr_params net/sctp/socket.c:2683 [inline]
> >  sctp_setsockopt+0x10e5f/0x11600 net/sctp/socket.c:4258
> >  sock_common_setsockopt+0x136/0x170 net/core/sock.c:3039
> >  __sys_setsockopt+0x4af/0x560 net/socket.c:1903
> >  __do_sys_setsockopt net/socket.c:1914 [inline]
> >  __se_sys_setsockopt net/socket.c:1911 [inline]
> >  __x64_sys_setsockopt+0x15c/0x1c0 net/socket.c:1911
> >  do_syscall_64+0x154/0x220 arch/x86/entry/common.c:287
> >  entry_SYSCALL_64_after_hwframe+0x44/0xa9
> > RIP: 0033:0x43fef9
> > RSP: 002b:00007ffc00d9bfd8 EFLAGS: 00000207 ORIG_RAX: 0000000000000036
> > RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 000000000043fef9
> > RDX: 0000000000000009 RSI: 0000000000000084 RDI: 0000000000000003
> > RBP: 00000000006ca018 R08: 0000000000000098 R09: 000000000000001c
> > R10: 0000000020000180 R11: 0000000000000207 R12: 0000000000401820
> > R13: 00000000004018b0 R14: 0000000000000000 R15: 0000000000000000
> >
> > Local variable description: ----dest@sctp_rcv
> > Variable was created at:
> >  sctp_rcv+0x13d/0x4d30 net/sctp/input.c:97
> >  ip_local_deliver_finish+0x874/0xec0 net/ipv4/ip_input.c:215
> > ==================================================================
> >
> >
> > ---
> > This bug is generated by a bot. It may contain errors.
> > See https://goo.gl/tpsmEJ for more information about syzbot.
> > syzbot engineers can be reached at syzkaller@xxxxxxxxxxxxxxxxx
> >
> > syzbot will keep track of this bug report. See:
> > https://goo.gl/tpsmEJ#bug-status-tracking for how to communicate with
> > syzbot.
> > syzbot can test patches for this bug, for details see:
> > https://goo.gl/tpsmEJ#testing-patches

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-- 
Alexander Potapenko
Software Engineer

Google Germany GmbH
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