linux-kernel - Re: [PATCH] scsi: ufs: core: Fix RPMB region size detection for UFS 2.2

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Message-ID: <ad7e2d0e5b219b4b2ef2aa7ab342513a2c66171f.camel@gmail.com>
Date: Fri, 30 Jan 2026 11:26:13 +0100
From: Bean Huo <huobean@...il.com>
To: Alexey Charkov <alchark@...pper.net>
Cc: Alim Akhtar <alim.akhtar@...sung.com>, Avri Altman
 <avri.altman@....com>,  Bart Van Assche <bvanassche@....org>, "James E.J.
 Bottomley" <James.Bottomley@...senpartnership.com>, "Martin K. Petersen"
 <martin.petersen@...cle.com>, Bean Huo <beanhuo@...ron.com>, Can Guo
 <can.guo@....qualcomm.com>,  linux-scsi@...r.kernel.org,
 linux-kernel@...r.kernel.org, stable@...r.kernel.org
Subject: Re: [PATCH] scsi: ufs: core: Fix RPMB region size detection for UFS
 2.2

On Thu, 2026-01-29 at 21:10 +0400, Alexey Charkov wrote:
> On Thu, Jan 29, 2026 at 8:53 PM Bean Huo <huobean@...il.com> wrote:
> > 
> > On Thu, 2026-01-29 at 11:38 +0400, Alexey Charkov wrote:
> > > +                       hba->dev_info.rpmb_region_size[0] =
> > > +                               get_unaligned_be64(desc_buf
> > > +                                       +
> > > RPMB_UNIT_DESC_PARAM_LOGICAL_BLK_COUNT)
> > > +                               <<
> > > desc_buf[RPMB_UNIT_DESC_PARAM_LOGICAL_BLK_SIZE]
> > > +                               >> 17; /* convert to 128 kBytes units */
> > > +               }
> > >          }
> > 
> > Hi Alexey,
> > 
> > thanks for your fix, I didn't notice there is UFS 2.x on the market which
> > will
> > use UFS OP-TEE RPMB framework.
> 
> Hi Bean, it turns out many of the UFS modules for Rockchip RK3576
> based devices are 2.2. I'm poking around the OP-TEE support on that
> platform, and discovered that the existing driver didn't see the RPMB
> at all, spent quite a bit of time trying to figure it out before
> spotting the difference between the two spec versions :)
> 
> > here is potential u8 Overflow, since for the UFS3.x+, it is u8 in unit
> > descriptor, but
> > 
> > 
> > The calculation can overflow for larger RPMB regions (>32MB):
> >    - A u8 can only represent up to 255 × 128KB = ~32MB
> >    - The shift result is assigned directly without bounds checking
> 
> The spec says it can only be up to 16MB maximum (see section 12.4.3.1
> RPMB Resources), so it should always fit. Happy to add a comment about
> that.
> 
> Best regards,
> Alexey

Hi Alexey,

Thanks for the clarification on the 16MB RPMB limit - that addresses the
overflow concern.

In your above operation, why not use SZ_128K to avoid the magic number?
BTW, please update your comment.

Kind regards,
Bean