linux-kernel - Re: [PATCH] ksmbd: remove unnecessary conditions

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Message-ID: <YTc4ClL0EwuHsPXP@google.com>
Date:   Tue, 7 Sep 2021 18:59:38 +0900
From:   Sergey Senozhatsky <senozhatsky@...omium.org>
To:     Dan Carpenter <dan.carpenter@...cle.com>
Cc:     Sergey Senozhatsky <senozhatsky@...omium.org>,
        Namjae Jeon <linkinjeon@...nel.org>,
        Steve French <sfrench@...ba.org>,
        Hyunchul Lee <hyc.lee@...il.com>, linux-cifs@...r.kernel.org,
        linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org
Subject: Re: [PATCH] ksmbd: remove unnecessary conditions

On (21/09/07 12:14), Dan Carpenter wrote:
[..]
> > > > 
> > > > 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.
> 
> But you've seen it now, right?

A linear search in array of 5 elements or a binary search in array of 340
elements? Yea, I saw it. I'd prefer one extra uid_valid(), if you'd ask
me - why call the function if we already know that it'll fail.