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

On Fri, Oct 12, 2018 at 5:29 AM Denis Kenzior [off-list ref] wrote:

Hi Nick,

quoted

@@ -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.

Thanks for the review.

Refer to
https://trustedcomputinggroup.org/wp-content/uploads/TPM-Main-Part-3-Commands_v1.2_rev116_01032011.pdf
for details.

 Can you cite the relevant section?

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?

int was exactly what I originally proposed:
https://github.com/ClangBuiltLinux/linux/issues/41#issuecomment-428365339.
If that works for you and the maintainers, I can send that in patch
form.

Regards,
-Denis

-- 
Thanks,
~Nick Desaulniers