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Message-ID: <1e1f7397d516f8b9780b08763f6338cd4ce83506.camel@kernel.org>
Subject: Re: [PATCH] ceph: fix decoding of client session messages flags
From:   Jeff Layton <jlayton@kernel.org>
To:     =?ISO-8859-1?Q?Lu=EDs?= Henriques <lhenriques@suse.de>,
        Xiubo Li <xiubli@redhat.com>, Ilya Dryomov <idryomov@gmail.com>
Cc:     ceph-devel@vger.kernel.org, linux-kernel@vger.kernel.org
Date:   Mon, 23 May 2022 12:19:27 -0400
In-Reply-To: <20220523160951.8781-1-lhenriques@suse.de>
References: <20220523160951.8781-1-lhenriques@suse.de>
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On Mon, 2022-05-23 at 17:09 +0100, Lu=EDs Henriques wrote:
> The cephfs kernel client started to show  the message:
>=20
>  ceph: mds0 session blocklisted
>=20
> when mounting a filesystem.  This is due to the fact that the session
> messages are being incorrectly decoded: the skip needs to take into
> account the 'len'.
>=20
> While there, fixed some whitespaces too.
>=20
> Fixes: e1c9788cb397 ("ceph: don't rely on error_string to validate blockl=
isted session.")
> Signed-off-by: Lu=EDs Henriques <lhenriques@suse.de>
> ---
>  fs/ceph/mds_client.c | 14 +++++++++-----
>  1 file changed, 9 insertions(+), 5 deletions(-)
>=20
> diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c
> index 00c3de177dd6..1bd3e1bb0fdf 100644
> --- a/fs/ceph/mds_client.c
> +++ b/fs/ceph/mds_client.c
> @@ -3375,13 +3375,17 @@ static void handle_session(struct ceph_mds_sessio=
n *session,
>  	}
> =20
>  	if (msg_version >=3D 5) {
> -		u32 flags;
> -		/* version >=3D 4, struct_v, struct_cv, len, metric_spec */
> -	        ceph_decode_skip_n(&p, end, 2 + sizeof(u32) * 2, bad);
> +		u32 flags, len;
> +
> +		/* version >=3D 4 */
> +		ceph_decode_skip_16(&p, end, bad); /* struct_v, struct_cv */
> +		ceph_decode_32_safe(&p, end, len, bad); /* len */
> +		ceph_decode_skip_n(&p, end, len, bad); /* metric_spec */
> +
>  		/* version >=3D 5, flags   */
> -                ceph_decode_32_safe(&p, end, flags, bad);
> +		ceph_decode_32_safe(&p, end, flags, bad);
>  		if (flags & CEPH_SESSION_BLOCKLISTED) {
> -		        pr_warn("mds%d session blocklisted\n", session->s_mds);
> +			pr_warn("mds%d session blocklisted\n", session->s_mds);
>  			blocklisted =3D true;
>  		}
>  	}

Good catch! Should we send this to stable too?

Reviewed-by: Jeff Layton <jlayton@kernel.org>