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 the EthanLog (container log relay) message parsing logic to safely handle malformed/binary data that may contain the protocol delimiter bytes, preventing potential memory corruption and ensuring the internal buffer is correctly compacted after consuming data.

Changes:

• Fix buffer compaction in processLogData() by correcting a memmove no-op so consumed bytes are actually removed.
• Harden processMessage() against invalid (<= 0) lengths and avoid unsigned wrap by using std::min<ssize_t>.
• Clarify the rationale for skipping empty/invalid fields when delimiter bytes appear in binary payloads.

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[Copilot]

Pull request overview

Copilot reviewed 1 out of 1 changed files in this pull request and generated no new comments.

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