linux-kernel - Re: [PATCH v2] seq_file: Unconditionally use vmalloc for buffer

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Date:   Tue, 16 Mar 2021 14:01:04 +0100
From:   Michal Hocko <mhocko@...e.com>
To:     Al Viro <viro@...iv.linux.org.uk>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Kees Cook <keescook@...omium.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Alexey Dobriyan <adobriyan@...il.com>,
        Lee Duncan <lduncan@...e.com>, Chris Leech <cleech@...hat.com>,
        Adam Nichols <adam@...mm-co.com>, linux-kernel@...r.kernel.org,
        linux-fsdevel@...r.kernel.org, linux-hardening@...r.kernel.org
Subject: Re: [PATCH v2] seq_file: Unconditionally use vmalloc for buffer

On Tue 16-03-21 12:43:12, Al Viro wrote:
[...]
> AFAICS, Kees wants to protect against ->show() instances stomping beyond
> the page size.  What I don't get is what do you get from using seq_file
> if you insist on doing raw access to the buffer rather than using
> seq_printf() and friends.  What's the point?

I do not think there is any and as you have said in other response we
should really make seq_get_buf internal thing to seq_file and be done
with that. If there is a missing functionality that users workaround by
abusing seq_get_buf then it should be added into seq_file interface.
-- 
Michal Hocko
SUSE Labs