linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Mike Kravetz <mike.kravetz@oracle.com>
To: Michal Hocko <mhocko@suse.com>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	Baolin Wang <baolin.wang@linux.alibaba.com>,
	Zhenguo Yao <yaozhenguo1@gmail.com>,
	Liu Yuntao <liuyuntao10@huawei.com>,
	Dan Carpenter <dan.carpenter@oracle.com>,
	Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH v2] hugetlb: clean up potential spectre issue warnings
Date: Wed, 23 Feb 2022 10:36:55 -0800	[thread overview]
Message-ID: <d4f8579f-c6a2-2bd5-2b55-63a05b50b0d2@oracle.com> (raw)
In-Reply-To: <YhXxXg45loivQF10@dhcp22.suse.cz>

On 2/23/22 00:33, Michal Hocko wrote:
> On Tue 22-02-22 13:53:56, Mike Kravetz wrote:
>> On 2/21/22 23:47, Michal Hocko wrote:
>> How about adding this note to the commit message?
>>
>> Note: these routines take a user specified value used as an index ONCE
>> during the boot process.  As a result, they can not be used as a general
>> method of exploitation.  Code changes are being made to eliminate warnings.
> 
> This would help but the question whether the change is worth remains.
> Does this change have any other advantage than silencing the warning?
> 

Silencing the warnings was the primary motivation for the change.  If Dan
has a plan to change smatch so that they are silenced for __init functions,
then it would be better to not make the changes to use array_index_nospec.

While making the changes, I shuffled the code a little and did not immediately
notice that it also 'fixes' an overflow/truncation issue when assigning an
unsigned long to int as addressed in [1].  We should probably make this change
whether or not we use array_index_nospec to silence warnings.

[1] https://lore.kernel.org/linux-mm/20220209134018.8242-1-liuyuntao10@huawei.com/

Thanks for your comments and suggestions!
-- 
Mike Kravetz

  reply	other threads:[~2022-02-23 18:37 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-02-18 21:29 [PATCH v2] hugetlb: clean up potential spectre issue warnings Mike Kravetz
2022-02-21  8:42 ` Michal Hocko
2022-02-21 20:24   ` Mike Kravetz
2022-02-22  7:47     ` Michal Hocko
2022-02-22 16:15       ` Schaufler, Casey
2022-02-22 16:36         ` Dan Carpenter
2022-02-23  8:35           ` Michal Hocko
2022-02-22 21:53       ` Mike Kravetz
2022-02-23  8:33         ` Michal Hocko
2022-02-23 18:36           ` Mike Kravetz [this message]
2022-02-24  9:31             ` Michal Hocko
2022-02-24  4:41         ` Andrew Morton

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=d4f8579f-c6a2-2bd5-2b55-63a05b50b0d2@oracle.com \
    --to=mike.kravetz@oracle.com \
    --cc=akpm@linux-foundation.org \
    --cc=baolin.wang@linux.alibaba.com \
    --cc=dan.carpenter@oracle.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mm@kvack.org \
    --cc=liuyuntao10@huawei.com \
    --cc=mhocko@suse.com \
    --cc=yaozhenguo1@gmail.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).