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Message-ID: <f281d4b831d71ebe86e48c0f45b82b05276bc655.camel@kernel.org>
Subject: Re: [PATCH] nfsd: make a copy of struct iattr before calling
 notify_change
From:   Jeff Layton <jlayton@kernel.org>
To:     Chuck Lever <chuck.lever@oracle.com>
Cc:     Zhi Li <yieli@redhat.com>, linux-nfs@vger.kernel.org,
        linux-kernel@vger.kernel.org
Date:   Fri, 19 May 2023 06:10:01 -0400
In-Reply-To: <20230517162645.254512-1-jlayton@kernel.org>
References: <20230517162645.254512-1-jlayton@kernel.org>
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On Wed, 2023-05-17 at 12:26 -0400, Jeff Layton wrote:
> notify_change can modify the iattr structure. In particular it can can
> end up setting ATTR_MODE when ATTR_KILL_SUID is already set, causing a
> BUG() if the same iattr is passed to notify_change more than once.
>=20
> Make a copy of the struct iattr before calling notify_change.
>=20
> Fixes: 34b91dda7124 NFSD: Make nfsd4_setattr() wait before returning NFS4=
ERR_DELAY
> Link: https://bugzilla.redhat.com/show_bug.cgi?id=3D2207969
> Reported-by: Zhi Li <yieli@redhat.com>
> Signed-off-by: Jeff Layton <jlayton@kernel.org>
> ---
>  fs/nfsd/vfs.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
>=20
> diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
> index c4ef24c5ffd0..ad0c5cd900b1 100644
> --- a/fs/nfsd/vfs.c
> +++ b/fs/nfsd/vfs.c
> @@ -538,7 +538,9 @@ nfsd_setattr(struct svc_rqst *rqstp, struct svc_fh *f=
hp,
> =20
>  	inode_lock(inode);
>  	for (retries =3D 1;;) {
> -		host_err =3D __nfsd_setattr(dentry, iap);
> +		struct iattr attrs =3D *iap;
> +
> +		host_err =3D __nfsd_setattr(dentry, &attrs);
>  		if (host_err !=3D -EAGAIN || !retries--)
>  			break;
>  		if (!nfsd_wait_for_delegreturn(rqstp, inode))

Zhi Li tested the test kernel for this today and this seems to have
fixed the issue. I think you can add:

Tested-by: Zhi Li <yieli@redhat.com>

Cheers,
Jeff