Re: [Xen-devel] [PATCH] xen/xsm: Shut up GCC 5.1.1 warnings.

[Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>]

On Wed, Sep 16, 2015 at 04:14:27PM +0100, Julien Grall wrote:
> Hi Konrad,
> 
> On 16/09/15 14:45, Konrad Rzeszutek Wilk wrote:
> > policydb.c: In function âuser_readâ:
> > policydb.c:1443:26: error: âbuf[2]â may be used uninitialized in this 
> > function [-Werror=maybe-uninitialized]
> >          usrdatum->bounds = le32_to_cpu(buf[2]);
> >                           ^
> > cc1: all warnings being treated as errors
> > 
> > Which makes no sense, as :
> >  1). A couple of lines above it is being filled (buf[2]).
> 
> Not in every case, if p->policyvers < POLICYDB_VERSION_BOUNDARY, buf[2]
> won't be initialized.
> 
> >  2). There are other instances of this which are not triggering this
> >      failure.
> > But GCC insists, and this patch stops the failures.
> > 
> > Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
> > ---
> >  xen/xsm/flask/ss/policydb.c | 2 ++
> >  1 file changed, 2 insertions(+)
> > 
> > diff --git a/xen/xsm/flask/ss/policydb.c b/xen/xsm/flask/ss/policydb.c
> > index a1060b1..cee259c 100644
> > --- a/xen/xsm/flask/ss/policydb.c
> > +++ b/xen/xsm/flask/ss/policydb.c
> > @@ -1274,6 +1274,7 @@ static int role_read(struct policydb *p, struct 
> > hashtab *h, void *fp)
> >      if ( rc < 0 )
> >          goto bad;
> >  
> > +    buf[2] = 0; /* To shut up compiler warnings. */
> 
> By doing this, you will override buf[2] when the policy version >=
> POLICYDB_VERSION_BOUNDARY.
> 
> >      len = le32_to_cpu(buf[0]);
> >      role->value = le32_to_cpu(buf[1]);
> >      if ( p->policyvers >= POLICYDB_VERSION_BOUNDARY )
> > @@ -1437,6 +1438,7 @@ static int user_read(struct policydb *p, struct 
> > hashtab *h, void *fp)
> >      if ( rc < 0 )
> >          goto bad;
> >  
> > +    buf[2] = 0; /* To shut up compiler warnings. */
> 
> Ditto.

Duh! I had it in a differente location in the earlier patch and
then moved down to make it after the 'goto bad'.

Thanks!
> 
> >      len = le32_to_cpu(buf[0]);
> >      usrdatum->value = le32_to_cpu(buf[1]);
> >      if ( p->policyvers >= POLICYDB_VERSION_BOUNDARY )
> > 
> 
> Regards,
> 
> -- 
> Julien Grall

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