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From: Andrey Ryabinin <ryabinin.a.a@gmail.com>
To: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Joe Perches <joe@perches.com>,
	Luis Henriques <luis.henriques@canonical.com>,
	Avijit Kanti Das <avijitnsec@codeaurora.org>,
	"David S . Miller" <davem@davemloft.net>,
	Ben Hutchings <ben@decadent.org.uk>,
	"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
	LKML <linux-kernel@vger.kernel.org>
Subject: Re: net: Zeroing the structure ethtool_wolinfo in ethtool_get_wol()
Date: Tue, 23 Aug 2016 19:38:28 +0300	[thread overview]
Message-ID: <CAPAsAGzNcGpf+TPcqymGNdB7POoz3Oj=VLwvvtz6yWJf1UX0=g@mail.gmail.com> (raw)
In-Reply-To: <1471966619.14381.21.camel@edumazet-glaptop3.roam.corp.google.com>

2016-08-23 18:36 GMT+03:00 Eric Dumazet <eric.dumazet@gmail.com>:
> On Tue, 2016-08-23 at 08:05 -0700, Joe Perches wrote:
>
>> A compiler does not have a standards based requirement to
>> initialize arbitrary padding bytes.
>>
>> I believe gcc always does zero all padding anyway.
>
> I would not worry for kernel code, because the amount of scrutiny there
> will be enough to 'fix potential bugs' [1], but a lot of user land code
> would suffer from various bugs as well that might sit there forever.
>
> [1] Also, most call sites in the kernel are using same call stack, so
> the offset of '1-7 leaked bytes' vs kernel stack is constant, making
> exploits quite challenging.
>
> Even if the current standards are lazy (are they, I did not check ?),
> security needs would call for a sane compiler behavior and changing the
> standards accordingly.
>

 C11 guarantees zeroed padding.

  reply	other threads:[~2016-08-23 16:39 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-08-23 13:41 CVE-2014-9900 fix is not upstream Luis Henriques
2016-08-23 13:41 ` net: Zeroing the structure ethtool_wolinfo in ethtool_get_wol() Luis Henriques
2016-08-23 14:06   ` Joe Perches
     [not found]     ` <CAOp4FwRxfE61azV78TZ7EKESQZzRU2Pfkc2GJ9j3MV7pr80qew@mail.gmail.com>
2016-08-23 15:40       ` Joe Perches
2016-08-23 14:21   ` Eric Dumazet
2016-08-23 15:05     ` Joe Perches
2016-08-23 15:36       ` Eric Dumazet
2016-08-23 16:38         ` Andrey Ryabinin [this message]
2016-08-23 16:46         ` Edward Cree
2016-08-23 17:15       ` Vegard Nossum
2016-08-23 17:33     ` Ben Hutchings
2016-08-23 16:40 ` CVE-2014-9900 fix is not upstream David Miller
2016-08-23 17:35   ` Ben Hutchings
2016-08-23 18:24     ` David Miller
2016-08-23 20:09       ` Al Viro
2016-08-23 20:34         ` Joe Perches
2016-08-23 20:49           ` Lennart Sorensen
2016-08-23 21:25             ` Al Viro
2016-08-24 14:03               ` Lennart Sorensen
2016-08-24 20:36                 ` Hannes Frederic Sowa
2016-08-25 12:40                   ` Johannes Berg
2016-08-25 12:41                     ` Johannes Berg
2016-08-25 15:14                   ` One Thousand Gnomes

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