linux-kernel - Re: [PATCH v7 01/25] kallsyms: avoid hardcoding the buffer size

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Message-ID: <YovkR56ZYsPhDW4q@kernel.org>
Date:   Mon, 23 May 2022 22:45:11 +0300
From:   Jarkko Sakkinen <jarkko@...nel.org>
To:     Miguel Ojeda <ojeda@...nel.org>
Cc:     Linus Torvalds <torvalds@...ux-foundation.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        rust-for-linux@...r.kernel.org, linux-kernel@...r.kernel.org,
        Boqun Feng <boqun.feng@...il.com>,
        Kees Cook <keescook@...omium.org>
Subject: Re: [PATCH v7 01/25] kallsyms: avoid hardcoding the buffer size

On Mon, May 23, 2022 at 04:01:14AM +0200, Miguel Ojeda wrote:
> From: Boqun Feng <boqun.feng@...il.com>
> 
> This makes it easier to update the size later on.
> 

This does not really conform to [1].

E.g.

"Declare KSY_NAME_LEN, which describes the maximum length for a kernel
symbol read by kallsyms from the input.  In read_symbol(), define the 
buffer to be of length "KSY_NAME_LEN + 1", which includes the terminator
character."

would be better.

> Furthermore, a static assert is added to ensure both are updated
> when that happens. The relationship used is one that keeps the new
> size (512+1) close to the original buffer size (500).

You must split this then into two patches:

1. A patch that re-defines the length with KSYM_NAME_LEN, i.e.
   #define KSYM_NAME_LEN 499
2. A patch which increases the size and reasoning for that.

Right now bundles two separate changes, which does not conform to [2].

BR, Jarkko