netdev - RE: [PATCH net-next] tipc: eliminate complaint of KMSAN uninit-value in tipc_conn_rcv

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Date:   Mon, 21 May 2018 13:02:37 +0000
From:   Jon Maloy <jon.maloy@...csson.com>
To:     David Miller <davem@...emloft.net>,
        "ying.xue@...driver.com" <ying.xue@...driver.com>
CC:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "syzkaller-bugs@...glegroups.com" <syzkaller-bugs@...glegroups.com>,
        "tipc-discussion@...ts.sourceforge.net" 
        <tipc-discussion@...ts.sourceforge.net>
Subject: RE: [PATCH net-next] tipc: eliminate complaint of KMSAN uninit-value
 in tipc_conn_rcv_sub



> -----Original Message-----
> From: netdev-owner@...r.kernel.org <netdev-owner@...r.kernel.org>
> On Behalf Of David Miller
> Sent: Saturday, May 19, 2018 23:00
> To: ying.xue@...driver.com
> Cc: netdev@...r.kernel.org; Jon Maloy <jon.maloy@...csson.com>;
> syzkaller-bugs@...glegroups.com; tipc-discussion@...ts.sourceforge.net
> Subject: Re: [PATCH net-next] tipc: eliminate complaint of KMSAN uninit-
> value in tipc_conn_rcv_sub
> 
> From: Ying Xue <ying.xue@...driver.com>
> Date: Fri, 18 May 2018 19:50:55 +0800
> 
> > As variable s of struct tipc_subscr type is not initialized in
> > tipc_conn_rcv_from_sock() before it is used in tipc_conn_rcv_sub(),
> > KMSAN reported the following uninit-value type complaint:
> 
> I agree with others that the short read is the bug.
> 
> You need to decide what should happen if not a full tipc_subscr object is
> obtained from the sock_recvmsg() call.
> 
> Proceeding to pass it on to tipc_conn_rcv_sub() cannot possibly be correct.
> 
> You're not getting what you are expecting from the peer, the memset() you
> are adding doesn't change that.
> 
> And once you get this badly sized read, what does that do to the stream of
> subsequent recvmsg calls here?

This socket/connection of type SOCK_SEQPACKET, so if anything like this happens, it is an error, and the connection should be aborted.
///jon