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 08:05:51 -0700 [thread overview]
Message-ID: <1539356751.2656.5.camel@linux.ibm.com> (raw)
In-Reply-To: <f83893d2-ed9b-613f-2768-1a975d28fe8b@gmail.com>
On Fri, 2018-10-12 at 07:29 -0500, Denis Kenzior wrote:
> Hi Nick,
>
> > @@ -123,7 +123,7 @@ static int TSS_rawhmac(unsigned char *digest,
> > const unsigned char *key,
> > */
> > static int TSS_authhmac(unsigned char *digest, const unsigned
> > char *key,
> > unsigned int keylen, unsigned char *h1,
> > - unsigned char *h2, unsigned char h3, ...)
> > + unsigned char h2, unsigned char *h3, ...)
> > {
> > unsigned char paramdigest[SHA1_DIGEST_SIZE];
> > struct sdesc *sdesc;
>
> So my concern here is that this actually breaks the natural argument
> order compared to what the specification uses. This in turn
> requires
> one to perform some mental gymnastics and I'm not sure that this is
> such
> a good idea. Refer to
> https://trustedcomputinggroup.org/wp-content/uploads/TPM-Main-Part-3-
> Commands_v1.2_rev116_01032011.pdf
> for details.
>
> Note that H3 is really the 'continueAuthSession' variable which is a
> bool. In the above specification BOOL has a size of 1, and
> TSS_authhmac already assigns a h3 to 'c' which is used for the actual
> hashing.
>
> 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.
James
next prev parent reply other threads:[~2018-10-12 15:06 UTC|newest]
Thread overview: 33+ 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
2018-10-11 16:02 ` Arnd Bergmann
2018-10-11 16:10 ` James Bottomley
2018-10-11 20:31 ` [PATCH] KEYS: trusted: fix -Wvarags warning ndesaulniers
2018-10-12 1:50 ` Nathan Chancellor
2018-10-12 16:55 ` Nick Desaulniers
2018-10-12 17:03 ` Nathan Chancellor
2018-10-12 12:29 ` Denis Kenzior
2018-10-12 15:05 ` James Bottomley [this message]
2018-10-12 15:13 ` Denis Kenzior
2018-10-12 15:22 ` James Bottomley
2018-10-12 15:44 ` Denis Kenzior
2018-10-12 15:46 ` James Bottomley
2018-10-12 15:53 ` Denis Kenzior
2018-10-12 16:01 ` James Bottomley
2018-10-12 17:14 ` Nick Desaulniers
2018-10-12 15:25 ` James Bottomley
2018-10-12 17:05 ` Nick Desaulniers
2018-10-12 17:17 ` Nick Desaulniers
2018-10-12 17:27 ` Denis Kenzior
2018-10-12 18:39 ` Nick Desaulniers
2018-10-12 17:02 ` Nick Desaulniers
2018-10-12 17:15 ` Denis Kenzior
2018-10-15 9:26 ` David Laight
2018-10-15 21:53 ` Nick Desaulniers
2018-10-16 8:13 ` David Laight
2018-10-22 23:43 ` [PATCH v2] " ndesaulniers
2018-10-23 0:00 ` Nathan Chancellor
2018-10-24 8:36 ` Jarkko Sakkinen
2018-10-29 17:54 ` Nick Desaulniers
2019-02-11 18:36 ` Nick Desaulniers
2019-02-12 23:12 ` Jarkko Sakkinen
2019-02-14 10:52 ` Jarkko Sakkinen
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