Re: [PATCH v2 1/2] of: property: Fix of_fwnode_get_reference_args() with negative index

[Rob Herring (Arm)]

On Thu, 18 Jun 2026 17:20:34 +0200, Alban Bedel wrote:
> fwnode_property_get_reference_args() should return -ENOENT when an out
> of bound index is passed. An issue arised with the OF backend because
> the OF API use signed indexes while the fwnode API use unsigned ones.
> When an index value greater the INT_MAX was passed to the OF backend
> it got casted to a negative value and it returned -EINVAL instead of
> -ENOENT. This patch add a check to of_fwnode_get_reference_args() to
> catch negative index before they are passed to the OF API and return
> -ENOENT right away.
> 
> This issue appeared when the following pattern was used in the LED
> subsystem:
> 
>     index = fwnode_property_match_string(fwnode, "led-names", name)
>     led_node = fwnode_find_reference(fwnode, "leds", index);
> 
> Unlike the same pattern with the OF API, this pattern implicitly cast
> the signed return value of fwnode_property_match_string() to an
> unsigned index leading to the above issue with the OF backend. It can
> be argued that the return value of fwnode_property_match_string()
> should be checked separately, but I think there is value in supporting
> such simple and straight to the point patterns.
> 
> Link: https://lore.kernel.org/linux-leds/aimVRwJPhlGxsIUj@tom-desktop/T/#mc43cbf7e0599991b56dd0d9680714d28d145fbc8
> Cc: Tommaso Merciai <tommaso.merciai.xr@xxxxxxxxxxxxxx>
> Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@xxxxxxxxxxxxxxxx>
> Signed-off-by: Alban Bedel <alban.bedel@xxxxxxxxxx>
> ---
> v2: Fixed comment block to follow linux coding style.
> ---
>  drivers/of/property.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 

Applied, thanks!