linux-kernel - Re: [-next] openvswitch BUILD_BUG

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CAEP_g=-XxgK9HVxvcaW3RS2zfa+77pB4cqfLFC0rcV7QJc+2BQ@mail.gmail.com>
Date:	Thu, 29 Aug 2013 18:11:25 -0700
From:	Jesse Gross <jesse@...ira.com>
To:	David Miller <davem@...emloft.net>
Cc:	geert@...ux-m68k.org, Andy Zhou <azhou@...ira.com>,
	"dev@...nvswitch.org" <dev@...nvswitch.org>,
	netdev <netdev@...r.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	linux-next@...r.kernel.org
Subject: Re: [-next] openvswitch BUILD_BUG_ON failed

On Thu, Aug 29, 2013 at 3:10 PM, David Miller <davem@...emloft.net> wrote:
> From: Jesse Gross <jesse@...ira.com>
> Date: Thu, 29 Aug 2013 14:42:22 -0700
>
>> On Thu, Aug 29, 2013 at 2:21 PM, Geert Uytterhoeven
>> <geert@...ux-m68k.org> wrote:
>>> However, I have some doubts about other alignment "enforcements":
>>>
>>> "__aligned(__alignof__(long))" makes the whole struct aligned to the
>>> alignment rule for "long":
>>>    1. This is only 2 bytes on m68k, i.e. != sizeof(long).
>>>    2. This is 4 bytes on many 32-bit platforms, which may be less than the
>>>       default alignment for "__be64" (cfr. some members of struct
>>>       ovs_key_ipv4_tunnel), so this may make those 64-bit members unaligned.
>>
>> Do any of those 32-bit architectures actually care about alignment of
>> 64 bit values? On 32-bit x86, a long is 32 bits but the alignment
>> requirement of __be64 is also 32 bit.
>
> All except x86-32 do, it is in fact the odd man out with respect to this
> issue.

Thanks, good to know.

Andy, do you want to modify your patch to just drop the alignment
specification as Geert suggested (but definitely keep the new build
assert that you added)? It's probably better to just send the patch to
netdev (against net-next) as well since you'll likely get better
comments there and we can fix this faster if you cut out the
middleman.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/