Re: [PATCH] ksmbd: remove unnecessary conditions

[Sergey Senozhatsky]

On (21/09/07 11:54), Dan Carpenter wrote:
> On Tue, Sep 07, 2021 at 05:06:04PM +0900, Sergey Senozhatsky wrote:
> > On (21/09/07 10:34), Dan Carpenter wrote:
> > >  
> > >  		id = le32_to_cpu(psid->sub_auth[psid->num_subauth - 1]);
> > > -		if (id >= 0) {
> > > -			/*
> > > -			 * Translate raw sid into kuid in the server's user
> > > -			 * namespace.
> > > -			 */
> > > -			uid = make_kuid(&init_user_ns, id);
> > > -
> > > -			/* If this is an idmapped mount, apply the idmapping. */
> > > -			uid = kuid_from_mnt(user_ns, uid);
> > > -			if (uid_valid(uid)) {
> > > -				fattr->cf_uid = uid;
> > > -				rc = 0;
> > > -			}
> > > +		/*
> > > +		 * Translate raw sid into kuid in the server's user
> > > +		 * namespace.
> > > +		 */
> > > +		uid = make_kuid(&init_user_ns, id);
> > 
> > Can make_kuid() return INVALID_UID? IOW, uid_valid(uid) here as well?
> 
> No need to check twice.  We're going to check at the end.
> 
> > 
> > > +
> > > +		/* If this is an idmapped mount, apply the idmapping. */
> > > +		uid = kuid_from_mnt(user_ns, uid);
> > > +		if (uid_valid(uid)) {
>                     ^^^^^^^^^^^^^^
> The check here is sufficient.

My point was more that a potentially invalid UID is passed to kuid_from_mnt()
and kgid_from_mnt(). I don't see map_id_up(), for example, checking that
passed UID is valid. So decided to double check.