linux-kernel - Re: [PATCH] KEYS: trusted: fix -Wvarags warning

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Date:   Fri, 12 Oct 2018 08:46:21 -0700
From:   James Bottomley <jejb@...ux.ibm.com>
To:     Denis Kenzior <denkenz@...il.com>, ndesaulniers@...gle.com,
        dhowells@...hat.com
Cc:     natechancellor@...il.com, ebiggers@...gle.com,
        Mimi Zohar <zohar@...ux.vnet.ibm.com>,
        James Morris <jmorris@...ei.org>,
        "Serge E. Hallyn" <serge@...lyn.com>,
        linux-integrity@...r.kernel.org, keyrings@...r.kernel.org,
        linux-security-module@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] KEYS: trusted: fix -Wvarags warning

On Fri, 2018-10-12 at 10:44 -0500, Denis Kenzior wrote:
> Hi James,
> 
> > > So instead of having unsigned char h3, can't we simply have bool
> > > h3 or unsigned int h3?
> > 
> > Given the ambiguity in the standards, the safe thing that will work
> > for all time and all potential compilers is a char *
> > 
> 
> All right.  You state this with certainty, but I'd still like you to 
> educate me why?
> 
>  From the links provided in the patch it seems that one cannot pass 
> char/float/short to va_start().  Fair enough.  So if we make h3 an 
> unsigned int, the issue goes away, no?

For the current version of clang, yes.  However, if we're fixing this
for good a char * pointer is the only guaranteed thing because it
mirrors current use in printf.

James