linux-hardening - Re: [PATCH] printf: Remove unused 'bprintf'

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Message-ID: <20241002104807.42b4b64e@gandalf.local.home>
Date: Wed, 2 Oct 2024 10:48:07 -0400
From: Steven Rostedt <rostedt@...dmis.org>
To: "Dr. David Alan Gilbert" <linux@...blig.org>
Cc: Andy Shevchenko <andy@...nel.org>, kees@...nel.org,
 akpm@...ux-foundation.org, pmladek@...e.com, linux@...musvillemoes.dk,
 senozhatsky@...omium.org, linux-hardening@...r.kernel.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH] printf: Remove unused 'bprintf'

On Wed, 2 Oct 2024 14:31:19 +0000
"Dr. David Alan Gilbert" <linux@...blig.org> wrote:

> > I am not familiar with tricks in BPF or ftrace code where this actually might
> > be implicitly called via a macro, but brief grep gives nothing that might point
> > to that.  
> 
> I've got an all-yes build (well, most after I took out broken stuff) booting
> with it, and it has CONFIG_BINARY_PRINTF=y and CONFIG_FTRACE=y .
> 
> trace_seq.c uses seq_buf_bprintf which uses bstr_printf rather than the plain
> bprintf() that I've deleted.
> Not sure where to dig in BPF, but I've had a fairly good grep around.

I believe it is safe to delete. It looks like bprintf() was added for
completeness, where as everything is just using the vbin_printf() directly.
bprintf() is nothing more than a wrapper around it in case someone wanted
to use binary prints directly. But I'm not sure there's a good use case for
it, as all users would likely need to add some code around it for
processing (like trace.c does).

Send a v2 and I could take it for v6.13.

-- Steve