fix(core): fix tropic reset by adding chip select handling
What the developer wrote
Authored by tychovrahe
fix(core): fix tropic reset by adding chip select handling
[no changelog]
What changed, and why it matters
This commit fixes how the Trezor hardware wallet resets its Tropic secure chip during startup. The change makes sure the chip-select line is pulled low before power is toggled and released afterward, which is needed for a clean reset. There is no direct evidence this is a security vulnerability rather than a reliability bug, but improper reset handling of a security chip could in theory lead to an unstable or unpredictable secure state.
Treat as a device-stability and potential security-hardening fix. Verify that the new reset sequence matches the Tropic01 vendor specification and that removing the 10 ms post-delay does not violate timing requirements. Consider adding a regression test or comment explaining the security relevance of the NSS handling.
Security signals we found
Reset-sequence change for a secure-element/coprocessor (Tropic01)
Chip-select line now explicitly managed during power-cycle reset
No changelog entry provided, limiting public context
Evidence from the diff
In core/embed/sec/tropic/stm32/tropic01.c, tropic01_reset() now drives TROPIC01_SPI_NSS_PIN to GPIO_PIN_RESET before enabling power, then drives it to GPIO_PIN_SET after the power pin is deasserted. The previous code only toggled the power pin and delayed 10 ms. The patch adds explicit SPI chip-select (NSS/CS) management around the power-cycle reset, which is a common requirement for SPI slaves that use CS as a reset or wake signal. The 10 ms post-reset delay was removed/replaced by the NSS deassertion.
Changed components
core/embed/sec/tropic/stm32/tropic01.cTropic01 secure chip driverTrezor Core firmware reset pathInspect captured patch +3 / −1
diff --git a/core/embed/sec/tropic/stm32/tropic01.c b/core/embed/sec/tropic/stm32/tropic01.c
index d273e6236..d9c36ddfc 100644
--- a/core/embed/sec/tropic/stm32/tropic01.c
+++ b/core/embed/sec/tropic/stm32/tropic01.c
@@ -39,10 +39,12 @@ static tropic_ui_progress_t ui_progress = NULL;
void tropic_set_ui_progress(tropic_ui_progress_t f) { ui_progress = f; }
void tropic01_reset(void) {
+ HAL_GPIO_WritePin(TROPIC01_SPI_NSS_PORT, TROPIC01_SPI_NSS_PIN,
+ GPIO_PIN_RESET);
HAL_GPIO_WritePin(TROPIC01_PWR_PORT, TROPIC01_PWR_PIN, GPIO_PIN_SET);
systick_delay_ms(10);
HAL_GPIO_WritePin(TROPIC01_PWR_PORT, TROPIC01_PWR_PIN, GPIO_PIN_RESET);
- systick_delay_ms(10);
+ HAL_GPIO_WritePin(TROPIC01_SPI_NSS_PORT, TROPIC01_SPI_NSS_PIN, GPIO_PIN_SET);
}
lt_ret_t lt_port_init(lt_l2_state_t *s2) {
Why this scored 29/100
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