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From: "NeilBrown" <neilb@suse.de>
To: "Fedor Pchelkin" <pchelkin@ispras.ru>
Cc: "Aleksandr Burakov" <a.burakov@rosalinux.ru>,
 "Chuck Lever" <chuck.lever@oracle.com>, "Jeff Layton" <jlayton@kernel.org>,
 linux-nfs@vger.kernel.org, "Dai Ngo" <Dai.Ngo@oracle.com>,
 linux-kernel@vger.kernel.org, "Tom Talpey" <tom@talpey.com>,
 "Olga Kornievskaia" <kolga@netapp.com>, lvc-project@linuxtesting.org
Subject: Re: [lvc-project] [PATCH] nfsd: fix memory leak in
 __cld_pipe_inprogress_downcall()
In-reply-to: <d6ac2546-cf4e-43c3-bc41-b62a61141339-pchelkin@ispras.ru>
References: <20240216134541.31577-1-a.burakov@rosalinux.ru>,
 <d6ac2546-cf4e-43c3-bc41-b62a61141339-pchelkin@ispras.ru>
Date: Mon, 19 Feb 2024 09:17:18 +1100
Message-id: <170829463835.1530.4794427167476868043@noble.neil.brown.name>

On Mon, 19 Feb 2024, Fedor Pchelkin wrote:
> Hello Aleksandr,
>=20
> On 24/02/16 04:45PM, Aleksandr Burakov wrote:
> > Dynamic memory, referenced by 'princhash.data' and 'name.data',=20
> > is allocated by calling function 'memdup_user' and lost=20
> > at __cld_pipe_inprogress_downcall() function return
>=20
> It is not actually lost. If nfs4_client_to_reclaim() fails and thus
> returns NULL - this error case is already properly handled.
>=20
> If nfs4_client_to_reclaim() succeeds then reference to the memory in
> question is passed to crp->cr_name.data and crp->cr_princhash.data
> correspondingly, and crp->cr_strhash entry is added to the list associated
> with nfsd_net. In this case the memory is supposed to be freed by
> nfs4_remove_reclaim_record(). See comment for nfs4_client_to_reclaim().
>=20
> So I think the patch just introduces a double-free.

Agreed - this patch is incorrect.

Thanks,
NeilBrown


>=20
> >=20
> > Found by Linux Verification Center (linuxtesting.org) with SVACE.
> >=20
> > Fixes: 11a60d159259 ("nfsd: add a "GetVersion" upcall for nfsdcld")
> > Signed-off-by: Aleksandr Burakov <a.burakov@rosalinux.ru>
> > ---
> >  fs/nfsd/nfs4recover.c | 2 ++
> >  1 file changed, 2 insertions(+)
> >=20
> > diff --git a/fs/nfsd/nfs4recover.c b/fs/nfsd/nfs4recover.c
> > index 2c060e0b1604..02663484782d 100644
> > --- a/fs/nfsd/nfs4recover.c
> > +++ b/fs/nfsd/nfs4recover.c
> > @@ -850,6 +850,8 @@ __cld_pipe_inprogress_downcall(const struct cld_msg_v=
2 __user *cmsg,
> >  			kfree(princhash.data);
> >  			return -EFAULT;
> >  		}
> > +		kfree(name.data);
> > +		kfree(princhash.data);
> >  		return nn->client_tracking_ops->msglen;
> >  	}
> >  	return -EFAULT;
> > --=20
> > 2.25.1
>=20
> --
> Fedor
>=20
>=20