netdev - Re: [PATCH v3] selinux: lsm: fix a missing-check bug in selinux_sb_eat_lsm

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Message-ID: <CAHC9VhSbS6_Hp6_k0qpqQTvyG29ADx+b7JoXjDgXViO9bRXVMA@mail.gmail.com>
Date:   Mon, 3 Jun 2019 16:59:38 -0400
From:   Paul Moore <paul@...l-moore.com>
To:     Gen Zhang <blackgod016574@...il.com>
Cc:     Al Viro <viro@...iv.linux.org.uk>,
        Stephen Smalley <sds@...ho.nsa.gov>,
        Eric Paris <eparis@...isplace.org>, omosnace@...hat.com,
        selinux@...r.kernel.org, linux-kernel@...r.kernel.org,
        netdev@...r.kernel.org, bpf@...r.kernel.org
Subject: Re: [PATCH v3] selinux: lsm: fix a missing-check bug in selinux_sb_eat_lsm_opts()

On Fri, May 31, 2019 at 10:45 PM Gen Zhang <blackgod016574@...il.com> wrote:
> On Sat, Jun 01, 2019 at 03:25:27AM +0100, Al Viro wrote:
> > On Sat, Jun 01, 2019 at 10:15:26AM +0800, Gen Zhang wrote:
> > > In selinux_sb_eat_lsm_opts(), 'arg' is allocated by kmemdup_nul(). It
> > > returns NULL when fails. So 'arg' should be checked. And 'mnt_opts'
> > > should be freed when error.
> >
> > What's the latter one for?  On failure we'll get to put_fs_context()
> > pretty soon, so
> >         security_free_mnt_opts(&fc->security);
> > will be called just fine.  Leaving it allocated on failure is fine...
> Paul Moore <paul@...l-moore.com> wrote:
> >It seems like we should also check for, and potentially free *mnt_opts
> >as the selinux_add_opt() error handling does just below this change,
> >yes?  If that is the case we might want to move that error handling
> >code to the bottom of the function and jump there on error.
> I am not familiar with this part. So could you please show the function
> call sequence?

I'm not sure I understand your question above, but I did review your
latest patch and agree with Ondrej's comment regarding the ret/rc
variable.  If you make that change I think we can merge this into
selinux/stable-5.2.

-- 
paul moore
www.paul-moore.com