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From: David Ahern <dsahern@gmail.com>
To: Jakub Kicinski <jakub.kicinski@netronome.com>,
	Eric Dumazet <eric.dumazet@gmail.com>
Cc: David Miller <davem@davemloft.net>,
	stephen@networkplumber.org, netdev@vger.kernel.org
Subject: Re: [Bug 199643] New: UBSAN: Undefined behaviour in ./include/net/route.h:240:2
Date: Thu, 7 Jun 2018 17:53:35 -0700	[thread overview]
Message-ID: <e6d18d55-2e35-b888-040f-b31117e38daf@gmail.com> (raw)
In-Reply-To: <20180607174923.13a11d08@cakuba.netronome.com>

On 6/7/18 5:49 PM, Jakub Kicinski wrote:
> On Thu, 7 Jun 2018 17:28:59 -0700, Eric Dumazet wrote:
>> On 06/07/2018 05:11 PM, David Miller wrote:
>>> From: Jakub Kicinski <jakub.kicinski@netronome.com>
>>> Date: Thu, 7 Jun 2018 17:06:23 -0700
>>>   
>>>> [  293.213661]  ip_send_unicast_reply+0x1b67/0x1d0e  
>>>
>>> This calls ip_setup_cork() which can NULL out the 'rt' route
>>> pointer.  Hmmm... :-/
>>>   
>>
>>
>> UBSAN seems unhappy  with dst being NULL in :
>>
>> dst_release(&rt->dst);
>>
>> But the code obviously is ready for dst being NULL, it is even documented :)
> 
> Oh, so the code depends on dst being the first member?  Would it make
> sense to just cast the pointer instead?
> 

I've been going the other way with 'rt to dst' and 'dst to rt'
transformations.

Perhaps UBSAN should be updated to understand that NULL + 0 is ok.

  reply	other threads:[~2018-06-08  0:53 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-05-07 17:34 Fw: [Bug 199643] New: UBSAN: Undefined behaviour in ./include/net/route.h:240:2 Stephen Hemminger
2018-05-08  4:12 ` David Miller
2018-05-08 14:52   ` David Ahern
2018-06-08  0:06     ` Jakub Kicinski
2018-06-08  0:11       ` David Miller
2018-06-08  0:28         ` Eric Dumazet
2018-06-08  0:49           ` Jakub Kicinski
2018-06-08  0:53             ` David Ahern [this message]
2018-06-08  1:02               ` Jakub Kicinski

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