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From: Paul Moore <paul@paul-moore.com>
Date: Tue, 27 Feb 2024 17:13:58 -0500
Message-ID: <CAHC9VhR2=bzVqHtcPH7-cSQRBnfphzzBQ4n9agXWMtasK9wh7Q@mail.gmail.com>
Subject: Re: [PATCH 2/2] AppArmor: Fix lsm_get_self_attr()
To: =?UTF-8?B?TWlja2HDq2wgU2FsYcO8bg==?= <mic@digikod.net>, 
	John Johansen <john.johansen@canonical.com>
Cc: Casey Schaufler <casey@schaufler-ca.com>, James Morris <jmorris@namei.org>, 
	"Serge E . Hallyn" <serge@hallyn.com>, linux-kernel@vger.kernel.org, 
	linux-security-module@vger.kernel.org, stable@vger.kernel.org
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On Tue, Feb 27, 2024 at 5:09=E2=80=AFPM Paul Moore <paul@paul-moore.com> wr=
ote:
> On Tue, Feb 27, 2024 at 11:01=E2=80=AFAM Paul Moore <paul@paul-moore.com>=
 wrote:
> > On Mon, Feb 26, 2024 at 2:59=E2=80=AFPM Paul Moore <paul@paul-moore.com=
> wrote:
> > > On Fri, Feb 23, 2024 at 4:07=E2=80=AFPM Paul Moore <paul@paul-moore.c=
om> wrote:
> > > > On Fri, Feb 23, 2024 at 2:06=E2=80=AFPM Micka=C3=ABl Sala=C3=BCn <m=
ic@digikod.net> wrote:
> > > > >
> > > > > aa_getprocattr() may not initialize the value's pointer in some c=
ase.
> > > > > As for proc_pid_attr_read(), initialize this pointer to NULL in
> > > > > apparmor_getselfattr() to avoid an UAF in the kfree() call.
> > > > >
> > > > > Cc: Casey Schaufler <casey@schaufler-ca.com>
> > > > > Cc: John Johansen <john.johansen@canonical.com>
> > > > > Cc: Paul Moore <paul@paul-moore.com>
> > > > > Cc: stable@vger.kernel.org
> > > > > Fixes: 223981db9baf ("AppArmor: Add selfattr hooks")
> > > > > Signed-off-by: Micka=C3=ABl Sala=C3=BCn <mic@digikod.net>
> > > > > ---
> > > > >  security/apparmor/lsm.c | 2 +-
> > > > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > > >
> > > > If you like John, I can send this up to Linus with the related SELi=
nux
> > > > fix, I would just need an ACK from you.
> > >
> > > Reviewed-by: Paul Moore <paul@paul-moore.com>
> > >
> > > This patch looks good to me, and while we've still got at least two
> > > (maybe three?) more weeks before v6.8 is tagged, I think it would be
> > > good to get this up to Linus ASAP.  I'll hold off for another day, bu=
t
> > > if we don't see any comment from John I'll go ahead and merge this an=
d
> > > send it up to Linus with the SELinux fix; I'm sure John wouldn't be
> > > happy if v6.8 went out the door without this fix.
> >
> > I just merged this into lsm/stable-6.8 and once the automated
> > build/test has done it's thing and come back clean I'll send this,
> > along with the associated SELinux fix, up to Linus.  Thanks all.
>
> In off-list discussions with Micka=C3=ABl today it was noted that this
> patch also needs a fixup to the commit description so I've replaced it
> with the following:
>
>   "In apparmor_getselfattr() when an invalid AppArmor
>    attribute is requested, or a value hasn't been explicitly
>    set for the requested attribute, the label passed to
>    aa_put_label() is not properly initialized which can cause
>    problems when the pointer value is non-NULL and AppArmor
>    attempts to drop a reference on the bogus label object."
>
> I've updated the commit in lsm/stable-6.8 and I'll be sending it to
> Linus shortly.
>
> > John, if this commit is problematic please let me know and I'll send a
> > fix or a revert.

I also just realized that both this patch and the SELinux have the
stable kernel marking which shouldn't be necessary as the LSM syscalls
are only present in the v6.8-rcX kernels.  I'm going to drop the
stable tagging, but leave the 'Fixes:' tag of course.

--=20
paul-moore.com