Re: [PATCH for-4.15 5/5] tools/xenstored: Silence coverity when using xs_state_* structures

[Julien Grall <julien@xxxxxxx>]

Hi Andrew,

On 25/02/2021 17:47, Andrew Cooper wrote:
> On 25/02/2021 17:41, Julien Grall wrote:
> > From: Julien Grall <jgrall@xxxxxxxxxx>
> >
> > Coverity will report unitialized values for every use of xs_state_*
> > structures in the save part. This can be prevented by using the [0]
> > rather than [] to define variable length array.
> >
> > Coverity-ID: 1472398
> > Coverity-ID: 1472397
> > Coverity-ID: 1472396
> > Coverity-ID: 1472395
> > Signed-off-by: Julien Grall <jgrall@xxxxxxxxxx>
> >
> > ---
> >
> >  From my understanding, the tools and the hypervisor already rely on GNU
> > extensions. So the change should be fine.
> >
> > If not, we can use the same approach as XEN_FLEX_ARRAY_DIM.
> Linux has recently purged the use of [0] because it causes sizeof() to
> do unsafe things.
Do you have a link to the Linux thread?

> Flexible array members is a C99 standard - are we sure that Coverity is
> doing something wrong with them?
I have run coverity with one of the structure switched to [0] and it 
removed the unitialized warning for that specific one.
So clearly coverity is not happy with []. Although, I am not sure why.

Do you have a suggestion how to approach the problem?

Cheers,

--
Julien Grall