linux-kernel - Re: KMSAN: uninit-value in strcmp

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Message-ID: <cb60d6f0-4e32-b360-d1f2-032ee7777fcd@windriver.com>
Date:   Tue, 8 May 2018 21:12:14 +0800
From:   Ying Xue <ying.xue@...driver.com>
To:     David Miller <davem@...emloft.net>,
        <syzbot+df0257c92ffd4fcc58cd@...kaller.appspotmail.com>
CC:     <jon.maloy@...csson.com>, <linux-kernel@...r.kernel.org>,
        <netdev@...r.kernel.org>, <syzkaller-bugs@...glegroups.com>,
        <tipc-discussion@...ts.sourceforge.net>
Subject: Re: KMSAN: uninit-value in strcmp

On 05/04/2018 03:22 AM, David Miller wrote:
> From: syzbot <syzbot+df0257c92ffd4fcc58cd@...kaller.appspotmail.com>
> Date: Thu, 03 May 2018 11:44:02 -0700
> 
>> 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
>>  strcmp+0xf7/0x160 lib/string.c:329
>>  tipc_nl_node_get_link+0x220/0x6f0 net/tipc/node.c:1881
>>  genl_family_rcv_msg net/netlink/genetlink.c:599 [inline]
> 
> Hmmm, TIPC_NL_LINK_GET uses tipc_nl_policy, which has a proper nesting
> entry for TIPC_NLA_LINK.  I wonder how the code goes about validating
> TIPC_NLA_LINK_NAME in such a case?  Does it?
> 
> This may be the problem.

David, you are right. This is absolutely a real bug. As you said, we
didn't validate TIPC_NLA_LINK_NAME attribute in tipc_nl_node_get_link()
at all.

I will submit a patch to fix the issue soon.

>