From 841d42400086aee1da39e9030deb4f28d414d2fd Mon Sep 17 00:00:00 2001 From: Chris Nourse Date: Mon, 6 Apr 2026 22:56:16 -0700 Subject: [PATCH] Fix NULL pointer dereference in STM32 SPI construct Move mark_deinit() before check_pins() so that self->sck is not NULLed after check_pins sets it. The previous ordering caused a NULL dereference of self->sck->altfn_index, crashing all STM32 boards that use SPI (including STM32F405 boards whose CIRCUITPY filesystem lives on external SPI flash). Fixes adafruit/circuitpython#10866 Co-Authored-By: Claude Opus 4.6 (1M context) --- ports/stm/common-hal/busio/SPI.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/ports/stm/common-hal/busio/SPI.c b/ports/stm/common-hal/busio/SPI.c index 1b86a9f55d5d4..24b65fbf54c0c 100644 --- a/ports/stm/common-hal/busio/SPI.c +++ b/ports/stm/common-hal/busio/SPI.c @@ -136,12 +136,13 @@ void common_hal_busio_spi_construct(busio_spi_obj_t *self, const mcu_pin_obj_t *sck, const mcu_pin_obj_t *mosi, const mcu_pin_obj_t *miso, bool half_duplex) { + // Ensure the object starts in its deinit state before check_pins sets + // self->sck, self->mosi, and self->miso. + common_hal_busio_spi_mark_deinit(self); + int periph_index = check_pins(self, sck, mosi, miso); SPI_TypeDef *SPIx = mcu_spi_banks[periph_index - 1]; - // Ensure the object starts in its deinit state. - common_hal_busio_spi_mark_deinit(self); - // Start GPIO for each pin GPIO_InitTypeDef GPIO_InitStruct = {0}; GPIO_InitStruct.Pin = pin_mask(sck->number);