What the developer wrote
Authored by cepetr
fix(core): increase prodtest stack size
[no changelog]
What changed, and why it matters
This commit doubles the stack memory size for the Trezor hardware wallet's production-test firmware from 12 KB to 24 KB. A stack that is too small can cause crashes (the commit notes 'Overflow causes UsageFault'). There is no direct evidence in the commit that this is exploitable as a security vulnerability, and the change appears to be a stability fix for a special manufacturing/QA mode rather than the normal user-facing wallet firmware.
Treat as a routine stability/hardening fix. Review whether the 12 KB stack overflow was reachable under normal prodtest operation or only under fault/debug conditions. If the prodtest image is signed and shipped, verify the fix is included in the next prodtest release. No immediate user action is indicated.
Security signals we found
Memory allocation change in a security-critical embedded device firmware
Reference to stack overflow causing UsageFault
No functional code change or vulnerability details provided in commit
Applies to prodtest (manufacturing/QA) linker script, not main firmware
Evidence from the diff
The patch changes a single linker script value for the STM32U5G prodtest build: .stack allocation in MAIN_RAM is increased from 12K to 24K. The comment explicitly states that overflow causes a UsageFault. This is a defensive hardening/stability change for the production-test firmware image. The diff does not show a specific overflow trigger, a CVE, an exploit path, or any functional code change; it only reserves more RAM for the stack.
Changed components
Trezor Core firmware production-test build for STM32U5Gcore/embed/sys/linker/stm32u5g/prodtest.ldInspect captured patch +1 / −1
diff --git a/core/embed/sys/linker/stm32u5g/prodtest.ld b/core/embed/sys/linker/stm32u5g/prodtest.ld
index 3e75c846b..7984304f1 100644
--- a/core/embed/sys/linker/stm32u5g/prodtest.ld
+++ b/core/embed/sys/linker/stm32u5g/prodtest.ld
@@ -69,7 +69,7 @@ SECTIONS {
} >FLASH AT>FLASH
.stack : ALIGN(8) {
- . = 12K; /* Overflow causes UsageFault */
+ . = 24K; /* Overflow causes UsageFault */
} >MAIN_RAM
.data : ALIGN(4) {
Why this scored 28/100
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