fix buffer overflow from deprecated MSP2_INAV_LOGIC_CONDITIONS

[stronnag]

User description

The deprecated MSP2_INAV_LOGIC_CONDITIONS generates a MSP output buffer of 896 bytes, which crashes the SITL and may result in undefined behaviour in the FC.

As there is a usable and safe replacement API, MSP2_INAV_LOGIC_CONDITIONS_SINGLE, this PR neuters MSP2_INAV_LOGIC_CONDITIONS by returning an "invalid" response.

In a future version, we should just remove MSP2_INAV_LOGIC_CONDITIONS completely (which would have the same effect).

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PR Type

Bug fix

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Description

• Prevents buffer overflow from deprecated MSP2_INAV_LOGIC_CONDITIONS command

• Returns invalid response instead of writing 896 bytes to buffer

• Directs users to use MSP2_INAV_LOGIC_CONDITIONS_SINGLE alternative

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Diagram Walkthrough

flowchart LR
  A["MSP2_INAV_LOGIC_CONDITIONS<br/>request"] -->|"Previously: write<br/>14*64 bytes"| B["Buffer overflow<br/>crash"]
  A -->|"Now: return false"| C["Invalid response<br/>safe"]
  D["MSP2_INAV_LOGIC_CONDITIONS_SINGLE"] -->|"Recommended<br/>alternative"| C

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File Walkthrough

Relevant files

Bug fix

fc_msp.c Disable deprecated MSP2_INAV_LOGIC_CONDITIONS command        src/main/fc/fc_msp.c Removed loop that wrote 14 logic condition entries (896 bytes total) to output buffer Replaced with single return false statement to indicate invalid/deprecated command Prevents buffer overflow that caused SITL crashes and undefined behavior Directs users to use MSP2_INAV_LOGIC_CONDITIONS_SINGLE API instead +1/-11

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[qodo-code-review]

PR Compliance Guide 🔍

(Compliance updated until commit 1bd1a20)

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Previous compliance checks

Compliance check up to commit 1bd1a20

[qodo-code-review]

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[stronnag]

Previously, a single call to MSP2_INAV_LOGIC_CONDITIONS would crash the SITL.
With this fix (returning no data), the test program is content (debug line count increments).

[stronnag]

And, FYI, the Configurator knows about the deprecation and uses the safe API:

grep -r MSPCodes.MSP2_INAV_LOGIC_CONDITIONS_SINGLE js
js/msp/MSPHelper.js:            case MSPCodes.MSP2_INAV_LOGIC_CONDITIONS_SINGLE:
js/msp/MSPHelper.js:            MSP.send_message(MSPCodes.MSP2_INAV_LOGIC_CONDITIONS_SINGLE, [idx], false, nextLogicCondition);
js/msp/MSPHelper.js:                    MSP.send_message(MSPCodes.MSP2_INAV_LOGIC_CONDITIONS_SINGLE, [idx], false, nextLogicCondition);
js/msp/MSPHelper.js:                    MSP.send_message(MSPCodes.MSP2_INAV_LOGIC_CONDITIONS_SINGLE, [idx], false, callback);