Problem Background

The current S26 module generates a large number of false positives when kernel source download fails:

1. cve-bin-tool detects CVEs based on version numbers -> generates many potential CVEs
2. Wait for kernel source download -> download fails/times out
3. Result: CVEs are reported but cannot be verified -> large number of false positives

Proposed Solution

Approach 1: Adjust Execution Order

Adjust the order of symbol extraction and CVE detection, first ensure verification capability before CVE detection.

Approach 2: Symbol-based CVE Filtering

When kernel source download fails, extract CVE-related function/symbol information from the NVD database for matching.

Implementation Suggestions

Modify Download Wait Logic

# Near line 268-270
if [[ "${lWAIT_CNT}" -gt 60 ]] || [[ -f "${TMP_DIR}"/linux_download_failed ]]; then
    print_output "[-] No valid kernel source file available ... switching to symbol-based verification"
    export KERNEL_SOURCE_AVAILABLE=0
else
    export KERNEL_SOURCE_AVAILABLE=1
fi

Add Degraded Verification Mode

if [[ "${KERNEL_SOURCE_AVAILABLE}" -eq 0 ]]; then
    symbol_name_verifier "${lCVE}" "${lK_VERSION}" "${lCVSS3}"
else
    symbol_verifier "${lCVE}" "${lK_VERSION}" "${lK_PATH}" "${lCVSS3}" "${lKERNEL_DIR}"
fi

Challenges and Limitations

Expected Results

• Reduce false positive rate: From hundreds of unverified CVEs to dozens with symbol matches
• Improve accuracy: Symbol-based verification is more accurate than pure version number matching
• Maintain coverage: Do not miss truly vulnerable CVEs