RDKEMW-24184 : Fix coverity issues (from copilot) in subttxrend-cc

[krithikasvraman]

Reason for change: Fix coverity issues in subttxrend-cc
Test Procedure: Regression tests
Risks: Low
Signed-off-by:krithika_venkataraman@comcast.com

[Copilot]

Pull request overview

This PR aims to address Coverity-reported issues in the subttxrend-cc closed caption command parser by adding additional bounds/length checks while scanning and parsing command bytes.

Changes:

• Add bounds handling in scanForRSTDLC() when encountering EXT1 sequences near the end of a block.
• Add early length validation in handleC0() for 3-byte C0 commands (e.g., P16) to avoid out-of-bounds reads.
• Update handleExtChar() to use the provided data_length and validate minimum length before reading the extended code byte.

Suppressed comments (1)

subttxrend-cc/src/CcCommandParser.cpp:682

• handleExtChar() returns 0 when data_length < 2, which can stall processBlock() (it increments i by consumed, so 0 results in an infinite loop). To avoid hanging on truncated EXT1 sequences, consume the remaining bytes instead of returning 0.

    if (data_length < 2)
    {
        return 0;
    }

---

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[Copilot]

Pull request overview

Copilot reviewed 1 out of 1 changed files in this pull request and generated 2 comments.

Suppressed comments (2)

Previously missed (1) — in code that hasn't changed since the last review.

subttxrend-cc/src/CcCommandParser.cpp:199

• scanForRSTDLC skips C0_EXT1 sequences using a fixed i += 2, but extended commands are variable-length (see handleExtChar/handleC2/handleC3). This can desynchronize the scan and cause false detection of C1_RST/C1_DLC inside an extended command payload, leading to unintended resets or delay cancels. Consider skipping the full extended-command length (with bounds checks) and continue the loop.

        if (data[i] == C0_EXT1)
        {
            i += 2;
            if (i >= data.size())
            {

subttxrend-cc/src/CcCommandParser.cpp:156

• The new early-exit paths for truncated commands (consumed == 0 break in processBlock, and handleExtChar returning 0 for short buffers) should have unit tests to ensure the parser neither crashes nor hangs on malformed/truncated service blocks (e.g., {C0_EXT1}; {C0_EXT1, 0x90}; {C0_P16, 0x41} etc.).

	if (consumed == 0)
	{
            break;
	}

[Copilot]

Copilot encountered an error and was unable to review this pull request. You can try again by re-requesting a review.

[Copilot]

Pull request overview

Copilot reviewed 1 out of 1 changed files in this pull request and generated 1 comment.

Suppressed comments (1)

Previously missed (1) — in code that hasn't changed since the last review.

subttxrend-cc/src/CcCommandParser.cpp:202

• scanForRSTDLC() treats EXT1 as a fixed 2-byte sequence (i += 2), but extended commands can be longer (e.g., C2 lengths 1–4; C3 can be 5/6/variable). This can desynchronize scanning and potentially mis-detect RST/DLC inside parameter bytes, causing incorrect buffer reset/cancel behavior.

        if (data[i] == C0_EXT1)
        {
            i += 2;
            if (i >= data.size())
            {
                break;
            }
        }

[Copilot]

🟢 Approval recommended

The changes are narrowly scoped defensive checks that mitigate concrete parsing edge cases without introducing interface changes or behavioral complexity.

Review details

• Files reviewed: 1/1 changed files
• Comments generated: 0 new
• Review effort level: Lite