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From: Nick Desaulniers <ndesaulniers@google.com>
To: denkenz@gmail.com
Cc: jejb@linux.ibm.com, dhowells@redhat.com,
	Nathan Chancellor <natechancellor@gmail.com>,
	Eric Biggers <ebiggers@google.com>,
	zohar@linux.vnet.ibm.com, jmorris@namei.org, serge@hallyn.com,
	linux-integrity@vger.kernel.org, keyrings@vger.kernel.org,
	linux-security-module@vger.kernel.org,
	LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] KEYS: trusted: fix -Wvarags warning
Date: Fri, 12 Oct 2018 18:39:47 +0000	[thread overview]
Message-ID: <CAKwvOdmL0kkZs7m+F5eXutVNqs0tjpKcKy-O4N8+-F2FOkL9gQ@mail.gmail.com> (raw)
In-Reply-To: <80837c90-0425-aadd-38d7-c3c866d29a0a@gmail.com>

On Fri, Oct 12, 2018 at 10:27 AM Denis Kenzior <denkenz@gmail.com> wrote:
>
> Hi Nick,
>
> >> 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.
> >
> > No. This is extremely well defined behavior in C.  In C, integral
> > types are NEVER promoted to pointer to integer types, only to larger
> > integral types through rules more complicated than the correct flags
> > to pass to `tar`.
> > https://xkcd.com/1168/
> >
>
> Ah right.  Thanks for the correction.  So looks like bool won't work for
> the same reasons.  But unsigned int should work right?  But then again
> this is a boolean value and if we want to be paranoid we can simply
> tweak the 'c = h3' assignment to be something like:
>
> c = !!h3;
>
> So in the end, I'm happy with int or unsigned int.

Thanks for the feedback.  I'll wait wait to see if James is also cool
with that approach, and if so, send a v2 based on the next-keys branch
in the security tree as per Nathan, with yours and his Suggested-by
tags.

-- 
Thanks,
~Nick Desaulniers

WARNING: multiple messages have this Message-ID (diff)
From: Nick Desaulniers <ndesaulniers@google.com>
To: denkenz@gmail.com
Cc: jejb@linux.ibm.com, dhowells@redhat.com,
	Nathan Chancellor <natechancellor@gmail.com>,
	Eric Biggers <ebiggers@google.com>,
	zohar@linux.vnet.ibm.com, jmorris@namei.org, serge@hallyn.com,
	linux-integrity@vger.kernel.org, keyrings@vger.kernel.org,
	linux-security-module@vger.kernel.org,
	LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] KEYS: trusted: fix -Wvarags warning
Date: Fri, 12 Oct 2018 11:39:47 -0700	[thread overview]
Message-ID: <CAKwvOdmL0kkZs7m+F5eXutVNqs0tjpKcKy-O4N8+-F2FOkL9gQ@mail.gmail.com> (raw)
In-Reply-To: <80837c90-0425-aadd-38d7-c3c866d29a0a@gmail.com>

On Fri, Oct 12, 2018 at 10:27 AM Denis Kenzior <denkenz@gmail.com> wrote:
>
> Hi Nick,
>
> >> 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.
> >
> > No. This is extremely well defined behavior in C.  In C, integral
> > types are NEVER promoted to pointer to integer types, only to larger
> > integral types through rules more complicated than the correct flags
> > to pass to `tar`.
> > https://xkcd.com/1168/
> >
>
> Ah right.  Thanks for the correction.  So looks like bool won't work for
> the same reasons.  But unsigned int should work right?  But then again
> this is a boolean value and if we want to be paranoid we can simply
> tweak the 'c = h3' assignment to be something like:
>
> c = !!h3;
>
> So in the end, I'm happy with int or unsigned int.

Thanks for the feedback.  I'll wait wait to see if James is also cool
with that approach, and if so, send a v2 based on the next-keys branch
in the security tree as per Nathan, with yours and his Suggested-by
tags.

-- 
Thanks,
~Nick Desaulniers

  reply	other threads:[~2018-10-12 18:39 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
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 [this message]
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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