drivers: led_strip: Check length before updating LED strip

Checks that the supplied length is valid for the given driver
before passing it to the update function

Signed-off-by: Jamie McCrae <spam@helper3000.net>

Author: thedjnK

drivers/led_strip/tlc5971.c

@@ -248,13 +248,6 @@ static int tlc5971_transmit_data(const struct device *dev, size_t num_pixels)
 
 static int tlc5971_update_rgb(const struct device *dev, struct led_rgb *pixels, size_t num_pixels)
 {
-	const struct tlc5971_config *cfg = dev->config;
-
-	if (num_pixels > cfg->num_pixels) {
-		LOG_ERR("invalid number of pixels, %zu vs actual %i", num_pixels, cfg->num_pixels);
-		return -EINVAL;
-	}
-
 	tlc5971_fill_data_buffer(dev, pixels, num_pixels);
 
 	return tlc5971_transmit_data(dev, num_pixels);

drivers/led_strip/ws2812_spi.c

@@ -39,7 +39,6 @@ LOG_MODULE_REGISTER(ws2812_spi);
 struct ws2812_spi_cfg {
 	struct spi_dt_spec bus;
 	uint8_t *px_buf;
-	size_t px_buf_size;
 	uint8_t one_frame;
 	uint8_t zero_frame;
 	uint8_t num_colors;
@@ -68,20 +67,6 @@ static inline void ws2812_spi_ser(uint8_t buf[8], uint8_t color,
 	}
 }
 
-/*
- * Returns true if and only if cfg->px_buf is big enough to convert
- * num_pixels RGB color values into SPI frames.
- */
-static inline bool num_pixels_ok(const struct ws2812_spi_cfg *cfg,
-				 size_t num_pixels)
-{
-	size_t nbytes;
-	bool overflow;
-
-	overflow = size_mul_overflow(num_pixels, cfg->num_colors * 8, &nbytes);
-	return !overflow && (nbytes <= cfg->px_buf_size);
-}
-
 /*
  * Latch current color values on strip and reset its state machines.
  */
@@ -98,7 +83,7 @@ static int ws2812_strip_update_rgb(const struct device *dev,
 	const uint8_t one = cfg->one_frame, zero = cfg->zero_frame;
 	struct spi_buf buf = {
 		.buf = cfg->px_buf,
-		.len = cfg->px_buf_size,
+		.len = (cfg->length * 8 * cfg->num_colors),
 	};
 	const struct spi_buf_set tx = {
 		.buffers = &buf,
@@ -108,10 +93,6 @@ static int ws2812_strip_update_rgb(const struct device *dev,
 	size_t i;
 	int rc;
 
-	if (!num_pixels_ok(cfg, num_pixels)) {
-		return -ENOMEM;
-	}
-
 	/*
 	 * Convert pixel data into SPI frames. Each frame has pixel data
 	 * in color mapping on-wire format (e.g. GRB, GRBW, RGB, etc).
@@ -235,7 +216,6 @@ static const struct led_strip_driver_api ws2812_spi_api = {
 	static const struct ws2812_spi_cfg ws2812_spi_##idx##_cfg = {	 \
 		.bus = SPI_DT_SPEC_INST_GET(idx, SPI_OPER(idx), 0),	 \
 		.px_buf = ws2812_spi_##idx##_px_buf,			 \
-		.px_buf_size = WS2812_SPI_BUFSZ(idx),			 \
 		.one_frame = WS2812_SPI_ONE_FRAME(idx),			 \
 		.zero_frame = WS2812_SPI_ZERO_FRAME(idx),		 \
 		.num_colors = WS2812_NUM_COLORS(idx),			 \

include/zephyr/drivers/led_strip.h

@@ -23,6 +23,7 @@
  * @{
  */
 
+#include <errno.h>
 #include <zephyr/types.h>
 #include <zephyr/device.h>
 
@@ -110,6 +111,16 @@ static inline int led_strip_update_rgb(const struct device *dev,
 	const struct led_strip_driver_api *api =
 		(const struct led_strip_driver_api *)dev->api;
 
+	/* Allow for out-of-tree drivers that do not have this function for 2 Zephyr releases
+	 * until making it mandatory, function added after Zephyr 3.6
+	 */
+	if (api->length != NULL) {
+		/* Ensure supplied pixel size is valid for this device */
+		if (api->length(dev) < num_pixels) {
+			return -ERANGE;
+		}
+	}
+
 	return api->update_rgb(dev, pixels, num_pixels);
 }