RDKEMW-15175: Prevent buffer overflow when binary data contains protocol delimiter bytes

[ks734]

Description

• processMessage(): add len < 0 guard that logs an error and returns -1, dropping the malformed message safely before any memcpy
• processMessage(): change std::min<size_t> to std::min<ssize_t> to prevent silent unsigned wrap of negative length values
• processLogData(): fix memmove(mMsgBuf, mMsgBuf, mMsgLen) no-op bug; correct source pointer to msgStart so consumed bytes are actually discarded from the buffer

Test Procedure

The crash is non-deterministic: it only occurs when the binary key bytes happen to contain a 0x1e or 0x1f byte

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Other (doesn't fit into the above categories - e.g. documentation updates)

Requires Bitbake Recipe changes?

• The base Bitbake recipe (meta-rdk-ext/recipes-containers/dobby/dobby.bb) must be modified to support the changes in this PR (beyond updating SRC_REV)

[Copilot]

Pull request overview

This PR hardens EthanLog message parsing to avoid memory corruption when binary/garbage data in the logging pipe contains delimiter bytes, and fixes a buffer-compaction bug so consumed bytes are actually removed from the receive buffer.

Changes:

• Fix buffer compaction in processLogData() by memmoving from the correct source pointer after discarding preamble bytes.
• Clarify/guard field handling to better tolerate malformed delimiter sequences.
• Add a defensive length guard in processMessage() and avoid unsigned wrap by using std::min<ssize_t> when capping the message length.

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[Copilot]

Pull request overview

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Pull request overview

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