On Wed, Oct 24, 2018 at 1:37 AM Jarkko Sakkinen
[off-list ref] wrote:

On Mon, 22 Oct 2018, ndesaulniers@google.com wrote:

quoted

Fixes the warning reported by Clang:
security/keys/trusted.c:146:17: warning: passing an object that
undergoes default
     argument promotion to 'va_start' has undefined behavior [-Wvarargs]
       va_start(argp, h3);
                      ^
security/keys/trusted.c:126:37: note: parameter of type 'unsigned
char' is declared here
unsigned char *h2, unsigned char h3, ...)
                              ^
Specifically, it seems that both the C90 (4.8.1.1) and C11 (7.16.1.4)
standards explicitly call this out as undefined behavior:

The parameter parmN is the identifier of the rightmost parameter in
the variable parameter list in the function definition (the one just
before the ...). If the parameter parmN is declared with ... or with a
type that is not compatible with the type that results after
application of the default argument promotions, the behavior is
undefined.

Link: https://github.com/ClangBuiltLinux/linux/issues/41
Link: https://www.eskimo.com/~scs/cclass/int/sx11c.html
Suggested-by: David Laight <redacted>
Suggested-by: Denis Kenzior <redacted>
Suggested-by: James Bottomley <redacted>
Suggested-by: Nathan Chancellor <redacted>
Signed-off-by: Nick Desaulniers <redacted>

Reviewed-by: Jarkko Sakkinen <redacted>

/Jarkko

Bumping the maintainers if this isn't already picked up?

-- 
Thanks,
~Nick Desaulniers