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Message-ID: <960792f1597622b59e1f7ae22884eaf72926363f.camel@suse.com>
Subject: Re: [PATCH] scsi: Let scsi_execute_cmd() mark args->sshdr as invalid
From:   Martin Wilck <mwilck@suse.com>
To:     Juergen Gross <jgross@suse.com>, linux-kernel@vger.kernel.org,
        linux-scsi@vger.kernel.org
Cc:     "James E.J. Bottomley" <jejb@linux.ibm.com>,
        "Martin K. Petersen" <martin.petersen@oracle.com>,
        stable@vger.kernel.org
Date:   Thu, 11 May 2023 18:00:31 +0200
In-Reply-To: <20230511123432.5793-1-jgross@suse.com>
References: <20230511123432.5793-1-jgross@suse.com>
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On Thu, 2023-05-11 at 14:34 +0200, Juergen Gross wrote:
> Some callers of scsi_execute_cmd() (like e.g. sd_spinup_disk()) are
> passing an uninitialized struct sshdr and don't look at the return
> value of scsi_execute_cmd() before looking at the contents of that
> struct.
>=20
> This can result in false positives when looking for specific error
> conditions.
>=20
> In order to fix that let scsi_execute_cmd() zero sshdr-
> >response_code,
> resulting in scsi_sense_valid() returning false.
>=20
> Cc: stable@vger.kernel.org
> Fixes: 3949e2f04262 ("scsi: simplify scsi_execute_req_flags")
> Signed-off-by: Juergen Gross <jgross@suse.com>

Reviewed-by: Martin Wilck <mwilck@suse.com>

> ---
> I'm not aware of any real error having happened due to this problem,
> but I thought it should be fixed anyway.
> I _think_ 3949e2f04262 was introducing the problem, but I'm not 100%
> sure it is really the commit to be blamed.
> ---
> =A0drivers/scsi/scsi_lib.c | 14 ++++++++++----
> =A01 file changed, 10 insertions(+), 4 deletions(-)
>=20
> diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
> index b7c569a42aa4..923336620bff 100644
> --- a/drivers/scsi/scsi_lib.c
> +++ b/drivers/scsi/scsi_lib.c
> @@ -209,11 +209,17 @@ int scsi_execute_cmd(struct scsi_device *sdev,
> const unsigned char *cmd,
> =A0=A0=A0=A0=A0=A0=A0=A0struct scsi_cmnd *scmd;
> =A0=A0=A0=A0=A0=A0=A0=A0int ret;
> =A0
> -=A0=A0=A0=A0=A0=A0=A0if (!args)
> +=A0=A0=A0=A0=A0=A0=A0if (!args) {
> =A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0args =3D &default_args;
> -=A0=A0=A0=A0=A0=A0=A0else if (WARN_ON_ONCE(args->sense &&
> -=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=
=A0=A0=A0=A0 args->sense_len !=3D
> SCSI_SENSE_BUFFERSIZE))
> -=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0return -EINVAL;
> +=A0=A0=A0=A0=A0=A0=A0} else {
> +=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0/* Mark sense data to be in=
valid. */
> +=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0if (args->sshdr)
> +=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0arg=
s->sshdr->response_code =3D 0;
> +
> +=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0if (WARN_ON_ONCE(args->sens=
e &&
> +=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=
=A0=A0=A0=A0=A0=A0=A0 args->sense_len !=3D
> SCSI_SENSE_BUFFERSIZE))
> +=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0ret=
urn -EINVAL;
> +=A0=A0=A0=A0=A0=A0=A0}
> =A0
> =A0=A0=A0=A0=A0=A0=A0=A0req =3D scsi_alloc_request(sdev->request_queue, o=
pf, args-
> >req_flags);
> =A0=A0=A0=A0=A0=A0=A0=A0if (IS_ERR(req))