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Subject: Re: [PATCH v2 1/2] scsi: ufs: core: Remove unnecessary if statement
From:   Bean Huo <huobean@gmail.com>
To:     Bart Van Assche <bvanassche@acm.org>, alim.akhtar@samsung.com,
        avri.altman@wdc.com, asutoshd@codeaurora.org, jejb@linux.ibm.com,
        martin.petersen@oracle.com, stanley.chu@mediatek.com,
        beanhuo@micron.com, tomas.winkler@intel.com, cang@codeaurora.org,
        daejun7.park@samsung.com
Cc:     linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org
Date:   Fri, 14 Oct 2022 22:30:48 +0200
In-Reply-To: <a1cd6719-a743-fc96-e0e7-364a52b62952@acm.org>
References: <20221010092937.520013-1-beanhuo@iokpp.de>
         <20221010092937.520013-2-beanhuo@iokpp.de>
         <a1cd6719-a743-fc96-e0e7-364a52b62952@acm.org>
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On Fri, 2022-10-14 at 11:37 -0700, Bart Van Assche wrote:
> > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=
=A0=C2=A0=C2=A0=C2=A0=C2=A0pr_err("Max General LU supported by UFS isn't
> > initialized\n");
> > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=
=A0=C2=A0=C2=A0=C2=A0=C2=A0return false;
> > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0}
> > -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0/* WB is available only for =
the logical unit from 0 to 7 */
> > -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0if (param_offset =3D=3D UNIT=
_DESC_PARAM_WB_BUF_ALLOC_UNITS)
> > -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=
=A0=C2=A0=C2=A0=C2=A0return lun < UFS_UPIU_MAX_WB_LUN_ID;
> > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0return lun =3D=3D UFS_U=
PIU_RPMB_WLUN || (lun < dev_info-
> > >max_lu_supported);
> > =C2=A0=C2=A0 }
>=20
> Hi Bean,
>=20
> I think the above patch reintroduces the stack overflow issue fixed
> by
> commit a2fca52ee640 ("scsi: ufs: WB is only available on LUN #0 to
> #7").
>=20
> How about reverting commit a2fca52ee640 and fixing the stack overflow
> issue in another way than by modifying ufs_is_valid_unit_desc_lun()?
>=20
> Thanks,
>=20
> Bart.

Hi Bart,=20

I double-checked the changelog and the stack overflow issue was double
fixed by your commit:

commit d3d9c4570285 ("scsi: ufs: Fix memory corruption by
ufshcd_read_desc_param()"),


For example, if the user wants to read wb_buf_alloc_units in the RPMB
unit descriptor,

parameter offset =3D 41, parameter size =3D 4,
buff_len =3D 45;

After ufshcd_query_descriptor_retry(), buff_len will be updated to 35.

param_offset > buff_len, then -EINVAL will be returned.

So we can safely remove this check, and if you still have concerns, I
can verify when I get back to the office.

Kind regards,
Bean