2024-01-10 22:25:58

by Frank Li

Subject: [PATCH 1/1] i3c: master: svc: return error when read length bigger than 255

RDTERM in MCTRL is 8 bits. Add a length check to prevent silent data errors
when the read length exceeds 255 bytes during each i3c_priv_xfer operation.

Signed-off-by: Frank Li <[email protected]>
---
drivers/i3c/master/svc-i3c-master.c | 5 +++++
1 file changed, 5 insertions(+)

diff --git a/drivers/i3c/master/svc-i3c-master.c b/drivers/i3c/master/svc-i3c-master.c
index bd10bb698da0f..181b56953fb28 100644
--- a/drivers/i3c/master/svc-i3c-master.c
+++ b/drivers/i3c/master/svc-i3c-master.c
@@ -1375,6 +1375,11 @@ static int svc_i3c_master_priv_xfers(struct i3c_dev_desc *dev,
cmd->len = xfers[i].len;
cmd->actual_len = xfers[i].rnw ? xfers[i].len : 0;
cmd->continued = (i + 1) < nxfers;
+
+ if (cmd->rnw && cmd->len > 255) {
+ dev_err(master->dev, "only support read less than 255 each xfer\n");
+ return -EINVAL;
+ }
}

mutex_lock(&master->lock);
--
2.34.1

2024-01-11 00:15:43

by Alexandre Belloni

Subject: Re: [PATCH 1/1] i3c: master: svc: return error when read length bigger than 255

On 10/01/2024 17:25:03-0500, Frank Li wrote:
> RDTERM in MCTRL is 8 bits. Add a length check to prevent silent data errors
> when the read length exceeds 255 bytes during each i3c_priv_xfer operation.
>
> Signed-off-by: Frank Li <[email protected]>
> ---
> drivers/i3c/master/svc-i3c-master.c | 5 +++++
> 1 file changed, 5 insertions(+)
>
> diff --git a/drivers/i3c/master/svc-i3c-master.c b/drivers/i3c/master/svc-i3c-master.c
> index bd10bb698da0f..181b56953fb28 100644
> --- a/drivers/i3c/master/svc-i3c-master.c
> +++ b/drivers/i3c/master/svc-i3c-master.c
> @@ -1375,6 +1375,11 @@ static int svc_i3c_master_priv_xfers(struct i3c_dev_desc *dev,
> cmd->len = xfers[i].len;
> cmd->actual_len = xfers[i].rnw ? xfers[i].len : 0;
> cmd->continued = (i + 1) < nxfers;
> +
> + if (cmd->rnw && cmd->len > 255) {
> + dev_err(master->dev, "only support read less than 255 each xfer\n");

What would be the end user action upon seeing this message? Is it actually
useful?

> + return -EINVAL;
> + }
> }
>
> mutex_lock(&master->lock);
> --
> 2.34.1
>

--
Alexandre Belloni, co-owner and COO, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com

2024-01-11 17:29:19

by Frank Li

Subject: Re: [PATCH 1/1] i3c: master: svc: return error when read length bigger than 255

On Thu, Jan 11, 2024 at 01:15:23AM +0100, Alexandre Belloni wrote:
> On 10/01/2024 17:25:03-0500, Frank Li wrote:
> > RDTERM in MCTRL is 8 bits. Add a length check to prevent silent data errors
> > when the read length exceeds 255 bytes during each i3c_priv_xfer operation.
> >
> > Signed-off-by: Frank Li <[email protected]>
> > ---
> > drivers/i3c/master/svc-i3c-master.c | 5 +++++
> > 1 file changed, 5 insertions(+)
> >
> > diff --git a/drivers/i3c/master/svc-i3c-master.c b/drivers/i3c/master/svc-i3c-master.c
> > index bd10bb698da0f..181b56953fb28 100644
> > --- a/drivers/i3c/master/svc-i3c-master.c
> > +++ b/drivers/i3c/master/svc-i3c-master.c
> > @@ -1375,6 +1375,11 @@ static int svc_i3c_master_priv_xfers(struct i3c_dev_desc *dev,
> > cmd->len = xfers[i].len;
> > cmd->actual_len = xfers[i].rnw ? xfers[i].len : 0;
> > cmd->continued = (i + 1) < nxfers;
> > +
> > + if (cmd->rnw && cmd->len > 255) {
> > + dev_err(master->dev, "only support read less than 255 each xfer\n");
>
> What would be the end user action upon seeing this message? Is it actually
> useful?

Hold on, I found an method. It may support > 255 transfer.

Frank Li

>
> > + return -EINVAL;
> > + }
> > }
> >
> > mutex_lock(&master->lock);
> > --
> > 2.34.1
> >
>
> --
> Alexandre Belloni, co-owner and COO, Bootlin
> Embedded Linux and Kernel engineering
> https://bootlin.com