netdev - Re: [PATCH net-next 2/2] af_iucv: Move sockaddr length checks to before accessing sa

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Message-Id: <20170623.145345.2050178619729566336.davem@davemloft.net>
Date:   Fri, 23 Jun 2017 14:53:45 -0400 (EDT)
From:   David Miller <davem@...emloft.net>
To:     socketcan@...tkopp.net
Cc:     jwi@...ux.vnet.ibm.com, netdev@...r.kernel.org,
        linux-s390@...r.kernel.org, schwidefsky@...ibm.com,
        heiko.carstens@...ibm.com, raspl@...ux.vnet.ibm.com,
        ubraun@...ux.vnet.ibm.com
Subject: Re: [PATCH net-next 2/2] af_iucv: Move sockaddr length checks to
 before accessing sa_family in bind and connect handlers

From: Oliver Hartkopp <socketcan@...tkopp.net>
Date: Fri, 23 Jun 2017 19:36:12 +0200

> 
> 
> On 06/23/2017 07:32 PM, Julian Wiedmann wrote:
>> From: Mateusz Jurczyk <mjurczyk@...gle.com>
>> 
>> Verify that the caller-provided sockaddr structure is large enough to
>> contain the sa_family field, before accessing it in bind() and connect()
>> handlers of the AF_IUCV socket. Since neither syscall enforces a minimum
>> size of the corresponding memory region, very short sockaddrs (zero or
>> one byte long) result in operating on uninitialized memory while
>> referencing .sa_family.
> 
> Won't it make sense to generally check the minimum length for .sa_family at a
> single point before fixing all called sites?

We had this discussion last week and we decided that putting it into
the handlers is the way to go for now.