On Sun, May 16, 2021 at 6:47 AM Bjorn Andersson
<bjorn.andersson@xxxxxxxxxx> wrote:
>
> In typec_mux_match() "nval" is assigned the number of elements in the
> "svid" fwnode property, then the variable is used to store the success
> of the read and finally attempts to loop between 0 and "success" - i.e.
> not at all - and the code returns indicating that no match was found.
>
> Fix this by using a separate variable to track the success of the read,
> to allow the loop to get a change to find a match.
>
> Fixes: 96a6d031ca99 ("usb: typec: mux: Find the muxes by also matching against the device node")
> Signed-off-by: Bjorn Andersson <bjorn.andersson@xxxxxxxxxx>
> ---
> drivers/usb/typec/mux.c | 7 ++++---
> 1 file changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/usb/typec/mux.c b/drivers/usb/typec/mux.c
> index 9da22ae3006c..8514bec7e1b8 100644
> --- a/drivers/usb/typec/mux.c
> +++ b/drivers/usb/typec/mux.c
> @@ -191,6 +191,7 @@ static void *typec_mux_match(struct fwnode_handle *fwnode, const char *id,
> bool match;
> int nval;
> u16 *val;
> + int ret;
> int i;
>
> /*
> @@ -218,10 +219,10 @@ static void *typec_mux_match(struct fwnode_handle *fwnode, const char *id,
> if (!val)
> return ERR_PTR(-ENOMEM);
>
> - nval = fwnode_property_read_u16_array(fwnode, "svid", val, nval);
> - if (nval < 0) {
> + ret = fwnode_property_read_u16_array(fwnode, "svid", val, nval);
> + if (ret < 0) {
> kfree(val);
> - return ERR_PTR(nval);
> + return ERR_PTR(ret);
> }
This changes the behaviour of the original code, i.e. nval can be
still positive but less than we got from previous call. Some fwnode
backends in some cases potentially can _successfully_ read less than
asked.
Perhaps
nval = ret;
or drop the patch.
> for (i = 0; i < nval; i++) {
--
With Best Regards,
Andy Shevchenko
