Re: KMSAN: uninit-value in __inet6_bind

[Dmitry Vyukov]

On Tue, Dec 11, 2018 at 1:41 AM syzbot
<syzbot+c56449ed3652e6720f30@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
>
> Hello,
>
> syzbot found the following crash on:
>
> HEAD commit:    3f06bda61398 kmsan: remove excessive KMSAN wrappers from a..
> git tree:       https://github.com/google/kmsan.git/master
> console output: https://syzkaller.appspot.com/x/log.txt?x=13ca6b05400000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=9b071100dcf8e641
> dashboard link: https://syzkaller.appspot.com/bug?extid=c56449ed3652e6720f30
> compiler:       clang version 8.0.0 (trunk 348261)
>
> Unfortunately, I don't have any reproducer for this crash yet.
>
> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: syzbot+c56449ed3652e6720f30@xxxxxxxxxxxxxxxxxxxxxxxxx

This looks like a bug in TIPC, +TIPC maintainers.

> Started in network mode
> Own node identity fe8000000000000000000000000000bb, cluster identity 4711
> ==================================================================
> BUG: KMSAN: uninit-value in __inet6_bind+0xb72/0x1ad0
> net/ipv6/af_inet6.c:340
> CPU: 0 PID: 8376 Comm: syz-executor3 Not tainted 4.20.0-rc5+ #111
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
> Google 01/01/2011
> Call Trace:
>   __dump_stack lib/dump_stack.c:77 [inline]
>   dump_stack+0x284/0x3b0 lib/dump_stack.c:113
>   kmsan_report+0x12d/0x290 mm/kmsan/kmsan.c:684
>   __msan_warning+0x76/0xc0 mm/kmsan/kmsan_instr.c:316
>   __inet6_bind+0xb72/0x1ad0 net/ipv6/af_inet6.c:340
>   inet6_bind+0x27f/0x390 net/ipv6/af_inet6.c:441
>   kernel_bind+0xc6/0xf0 net/socket.c:3230
>   udp_sock_create6+0x2ee/0x890 net/ipv6/ip6_udp_tunnel.c:39
>   udp_sock_create include/net/udp_tunnel.h:61 [inline]
>   tipc_udp_enable+0x166f/0x1d70 net/tipc/udp_media.c:742
>   tipc_enable_bearer net/tipc/bearer.c:302 [inline]
>   __tipc_nl_bearer_enable+0x1213/0x1da0 net/tipc/bearer.c:897
>   tipc_nl_bearer_enable+0x6c/0xb0 net/tipc/bearer.c:905
>   genl_family_rcv_msg net/netlink/genetlink.c:601 [inline]
>   genl_rcv_msg+0x185f/0x1a60 net/netlink/genetlink.c:626
>   netlink_rcv_skb+0x444/0x640 net/netlink/af_netlink.c:2477
>   genl_rcv+0x63/0x80 net/netlink/genetlink.c:637
>   netlink_unicast_kernel net/netlink/af_netlink.c:1310 [inline]
>   netlink_unicast+0xfc5/0x10a0 net/netlink/af_netlink.c:1336
>   netlink_sendmsg+0x1298/0x13e0 net/netlink/af_netlink.c:1917
>   sock_sendmsg_nosec net/socket.c:621 [inline]
>   sock_sendmsg net/socket.c:631 [inline]
>   ___sys_sendmsg+0xdbc/0x11d0 net/socket.c:2116
>   __sys_sendmsg net/socket.c:2154 [inline]
>   __do_sys_sendmsg net/socket.c:2163 [inline]
>   __se_sys_sendmsg+0x305/0x460 net/socket.c:2161
>   __x64_sys_sendmsg+0x4a/0x70 net/socket.c:2161
>   do_syscall_64+0xcd/0x110 arch/x86/entry/common.c:291
>   entry_SYSCALL_64_after_hwframe+0x63/0xe7
> RIP: 0033:0x457659
> Code: fd b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 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 cb b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00
> RSP: 002b:00007f82ebc52c78 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
> RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000457659
> RDX: 0000000000000000 RSI: 00000000200008c0 RDI: 0000000000000003
> RBP: 000000000072bf00 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000246 R12: 00007f82ebc536d4
> R13: 00000000004c421b R14: 00000000004d7160 R15: 00000000ffffffff
>
> Local variable description: ----udp6_addr@udp_sock_create6
> Variable was created at:
>   udp_sock_create6+0x80/0x890 net/ipv6/ip6_udp_tunnel.c:17
>   udp_sock_create include/net/udp_tunnel.h:61 [inline]
>   tipc_udp_enable+0x166f/0x1d70 net/tipc/udp_media.c:742
> ==================================================================
>
>
> ---
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