KMSAN: uninit-value in __inet6_bind

[syzbot]

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+c56449...@syzkaller.appspotmail.com

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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[Dmitry Vyukov]

On Tue, Dec 11, 2018 at 1:41 AM syzbot
<syzbot+c56449...@syzkaller.appspotmail.com> 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+c56449...@syzkaller.appspotmail.com

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

> --
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> For more options, visit https://groups.google.com/d/optout.

[Cong Wang]

On Tue, Dec 11, 2018 at 1:04 AM Dmitry Vyukov <dvy...@google.com> wrote:
>
> On Tue, Dec 11, 2018 at 1:41 AM syzbot
> <syzbot+c56449...@syzkaller.appspotmail.com> 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+c56449...@syzkaller.appspotmail.com
>
> This looks like a bug in TIPC, +TIPC maintainers.
>

It looks more like udp_sock_create6() doesn't initialize
udp6_addr.sin6_scope_id.

[Jon Maloy]

> -----Original Message-----
> From: Cong Wang <xiyou.w...@gmail.com>
> Sent: 12-Dec-18 01:17
> To: Dmitry Vyukov <dvy...@google.com>
> Cc: syzbot+c56449...@syzkaller.appspotmail.com; Jon Maloy
> <jon....@ericsson.com>; Ying Xue <ying...@windriver.com>; tipc-
> discu...@lists.sourceforge.net; David Miller <da...@davemloft.net>;
> Alexey Kuznetsov <kuz...@ms2.inr.ac.ru>; LKML <linux-
> ker...@vger.kernel.org>; Linux Kernel Network Developers
> <net...@vger.kernel.org>; syzkall...@googlegroups.com; Hideaki
> YOSHIFUJI <yosh...@linux-ipv6.org>
> Subject: Re: KMSAN: uninit-value in __inet6_bind

Unfortunately udp_sock_create6() has no way of knowing this value, because struct udp_port_cfg is missing a field sin6_scope_id.
So this has to be fixed first by adding this field to the struct, and then setting it correctly in all current users.

///jon

[Eric Dumazet]

Do we reasons to believe values other than 0 are needed ?

[Jon Maloy]

For TIPC it is ok with 0.

///jon

[syzbot]

syzbot has found a reproducer for the following crash on:

HEAD commit: 0a602458c72c kmsan: random: another take at unpoisoning CR..
git tree: https://github.com/google/kmsan.git/master
console output: https://syzkaller.appspot.com/x/log.txt?x=129e1035400000

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)

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=10a97b2b400000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=108ec72b400000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+c56449...@syzkaller.appspotmail.com

audit: type=1800 audit(1545030606.944:30): pid=6407 uid=0 auid=4294967295
ses=4294967295 subj==unconfined op=collect_data cause=failed(directio)
comm="startpar" name="rmnologin" dev="sda1" ino=2423 res=0

Started in network mode
Own node identity fe8000000000000000000000000000bb, cluster identity 4711
==================================================================

BUG: KMSAN: uninit-value in __inet6_bind+0xb35/0x1a30
net/ipv6/af_inet6.c:340
CPU: 1 PID: 6557 Comm: syz-executor447 Not tainted 4.20.0-rc5+ #2

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+0x1c9/0x220 lib/dump_stack.c:113
kmsan_report+0x12d/0x290 mm/kmsan/kmsan.c:682
__msan_warning+0x76/0xc0 mm/kmsan/kmsan_instr.c:316
__inet6_bind+0xb35/0x1a30 net/ipv6/af_inet6.c:340
inet6_bind+0x206/0x300 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+0xf80/0x1060 net/netlink/af_netlink.c:1336
netlink_sendmsg+0x129d/0x1310 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: 0033:0x444199
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 1b d8 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007ffe96b1eb28 EFLAGS: 00000213 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00000000004002e0 RCX: 0000000000444199

RDX: 0000000000000000 RSI: 00000000200008c0 RDI: 0000000000000003

RBP: 00000000006ce018 R08: 0000000000000000 R09: 00000000004002e0
R10: 0000000000000000 R11: 0000000000000213 R12: 0000000000401e40
R13: 0000000000401ed0 R14: 0000000000000000 R15: 0000000000000000