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From: James Bottomley <jejb@linux.ibm.com>
To: Denis Kenzior <denkenz@gmail.com>,
	ndesaulniers@google.com, dhowells@redhat.com
Cc: natechancellor@gmail.com, ebiggers@google.com,
	Mimi Zohar <zohar@linux.vnet.ibm.com>,
	James Morris <jmorris@namei.org>,
	"Serge E. Hallyn" <serge@hallyn.com>,
	linux-integrity@vger.kernel.org, keyrings@vger.kernel.org,
	linux-security-module@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH] KEYS: trusted: fix -Wvarags warning
Date: Fri, 12 Oct 2018 15:22:39 +0000	[thread overview]
Message-ID: <1539357759.2656.7.camel@linux.ibm.com> (raw)
In-Reply-To: <fc23168b-7275-bae0-6039-04e261b3cbad@gmail.com>

On Fri, 2018-10-12 at 10:13 -0500, Denis Kenzior wrote:
> Hi James,
> 
> > > So can't we simply use 'bool' or uint32 as the type for h3
> > > instead of re-ordering everything
> > 
> > The problem is the standard is ambiguious.  The only thing that's
> > guaranteed to work for all time is a char *.  If you want to keep
> > the order, what I'd suggest is inserting a dummy pointer argument
> > which is always expected to be NULL between the h3 and the varargs.
> 
> So maybe I'm misunderstanding something, but the issue seems to be
> that unsigned char is promoted to 'unsigned char *' by Clang and
> probably unsigned int or int by gcc.
> 
> 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 *

James

WARNING: multiple messages have this Message-ID (diff)
From: James Bottomley <jejb@linux.ibm.com>
To: Denis Kenzior <denkenz@gmail.com>,
	ndesaulniers@google.com, dhowells@redhat.com
Cc: natechancellor@gmail.com, ebiggers@google.com,
	Mimi Zohar <zohar@linux.vnet.ibm.com>,
	James Morris <jmorris@namei.org>,
	"Serge E. Hallyn" <serge@hallyn.com>,
	linux-integrity@vger.kernel.org, keyrings@vger.kernel.org,
	linux-security-module@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH] KEYS: trusted: fix -Wvarags warning
Date: Fri, 12 Oct 2018 08:22:39 -0700	[thread overview]
Message-ID: <1539357759.2656.7.camel@linux.ibm.com> (raw)
In-Reply-To: <fc23168b-7275-bae0-6039-04e261b3cbad@gmail.com>

On Fri, 2018-10-12 at 10:13 -0500, Denis Kenzior wrote:
> Hi James,
> 
> > > So can't we simply use 'bool' or uint32 as the type for h3
> > > instead of re-ordering everything
> > 
> > The problem is the standard is ambiguious.  The only thing that's
> > guaranteed to work for all time is a char *.  If you want to keep
> > the order, what I'd suggest is inserting a dummy pointer argument
> > which is always expected to be NULL between the h3 and the varargs.
> 
> So maybe I'm misunderstanding something, but the issue seems to be
> that unsigned char is promoted to 'unsigned char *' by Clang and
> probably unsigned int or int by gcc.
> 
> 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 *

James


  reply	other threads:[~2018-10-12 15:22 UTC|newest]

Thread overview: 68+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-10-09 22:11 undefined behavior (-Wvarargs) in security/keys/trusted.c#TSS_authhmac() Nick Desaulniers
2018-10-09 22:11 ` Nick Desaulniers
2018-10-11 16:02 ` Arnd Bergmann
2018-10-11 16:02   ` Arnd Bergmann
2018-10-11 16:10   ` James Bottomley
2018-10-11 16:10     ` James Bottomley
2018-10-11 20:31     ` [PATCH] KEYS: trusted: fix -Wvarags warning ndesaulniers
2018-10-11 20:31       ` ndesaulniers
2018-10-12  1:50       ` Nathan Chancellor
2018-10-12  1:50         ` Nathan Chancellor
2018-10-12 16:55         ` Nick Desaulniers
2018-10-12 16:55           ` Nick Desaulniers
2018-10-12 17:03           ` Nathan Chancellor
2018-10-12 17:03             ` Nathan Chancellor
2018-10-12 12:29       ` Denis Kenzior
2018-10-12 12:29         ` Denis Kenzior
2018-10-12 15:05         ` James Bottomley
2018-10-12 15:05           ` James Bottomley
2018-10-12 15:13           ` Denis Kenzior
2018-10-12 15:13             ` Denis Kenzior
2018-10-12 15:22             ` James Bottomley [this message]
2018-10-12 15:22               ` James Bottomley
2018-10-12 15:44               ` Denis Kenzior
2018-10-12 15:44                 ` Denis Kenzior
2018-10-12 15:46                 ` James Bottomley
2018-10-12 15:46                   ` James Bottomley
2018-10-12 15:53                   ` Denis Kenzior
2018-10-12 15:53                     ` Denis Kenzior
2018-10-12 16:01                     ` James Bottomley
2018-10-12 16:01                       ` James Bottomley
2018-10-12 17:14                       ` Nick Desaulniers
2018-10-12 17:14                         ` Nick Desaulniers
2018-10-12 15:25             ` James Bottomley
2018-10-12 15:25               ` James Bottomley
2018-10-12 17:05             ` Nick Desaulniers
2018-10-12 17:05               ` Nick Desaulniers
2018-10-12 17:17               ` Nick Desaulniers
2018-10-12 17:17                 ` Nick Desaulniers
2018-10-12 17:27               ` Denis Kenzior
2018-10-12 17:27                 ` Denis Kenzior
2018-10-12 18:39                 ` Nick Desaulniers
2018-10-12 18:39                   ` Nick Desaulniers
2018-10-12 17:02         ` Nick Desaulniers
2018-10-12 17:02           ` Nick Desaulniers
2018-10-12 17:15           ` Denis Kenzior
2018-10-12 17:15             ` Denis Kenzior
2018-10-15  9:26       ` David Laight
2018-10-15  9:26         ` David Laight
2018-10-15  9:26         ` David Laight
2018-10-15 21:53         ` Nick Desaulniers
2018-10-15 21:53           ` Nick Desaulniers
2018-10-16  8:13           ` David Laight
2018-10-16  8:13             ` David Laight
2018-10-16  8:13             ` David Laight
2018-10-22 23:43             ` [PATCH v2] " ndesaulniers
2018-10-22 23:43               ` ndesaulniers
2018-10-23  0:00               ` Nathan Chancellor
2018-10-23  0:00                 ` Nathan Chancellor
2018-10-24  8:36               ` Jarkko Sakkinen
2018-10-24  8:36                 ` Jarkko Sakkinen
2018-10-29 17:54                 ` Nick Desaulniers
2018-10-29 17:54                   ` Nick Desaulniers
2019-02-11 18:36                   ` Nick Desaulniers
2019-02-11 18:36                     ` Nick Desaulniers
2019-02-12 23:12                     ` Jarkko Sakkinen
2019-02-12 23:12                       ` Jarkko Sakkinen
2019-02-14 10:52                       ` Jarkko Sakkinen
2019-02-14 10:52                         ` Jarkko Sakkinen

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