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Fix unaligned reads during metadata search

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This commit is contained in:
Will Miles
2025-10-25 09:57:03 -04:00
parent 5ca10f35d1
commit 0c22163fd9
1 changed files with 40 additions and 33 deletions
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73
wled00/wled_metadata.cpp
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@@ -80,40 +80,47 @@ const __FlashStringHelper* brandString = FPSTR(brandString_s);
* @return true if structure was found and extracted, false otherwise
*/
bool findWledMetadata(const uint8_t* binaryData, size_t dataSize, wled_metadata_t* extractedDesc) {
if (!binaryData || !extractedDesc || dataSize < sizeof(wled_metadata_t)) {
return false;
}
for (size_t offset = 0; offset <= dataSize - sizeof(wled_metadata_t); offset++) {
const wled_metadata_t* custom_desc = (const wled_metadata_t*)(binaryData + offset);
// Check for magic number
if (custom_desc->magic == WLED_CUSTOM_DESC_MAGIC) {
// Found potential match, validate version
if (custom_desc->desc_version != WLED_CUSTOM_DESC_VERSION) {
DEBUG_PRINTF_P(PSTR("Found WLED structure at offset %u but version mismatch: %u\n"),
offset, custom_desc->desc_version);
continue;
}
// Validate hash using runtime function
uint32_t expected_hash = djb2_hash_runtime(custom_desc->release_name);
if (custom_desc->hash != expected_hash) {
DEBUG_PRINTF_P(PSTR("Found WLED structure at offset %u but hash mismatch\n"), offset);
continue;
}
// Valid structure found - copy entire structure
memcpy(extractedDesc, custom_desc, sizeof(wled_metadata_t));
DEBUG_PRINTF_P(PSTR("Extracted WLED structure at offset %u: '%s'\n"),
offset, extractedDesc->release_name);
return true;
}
}
DEBUG_PRINTLN(F("No WLED custom description found in binary"));
if (!binaryData || !extractedDesc || dataSize < sizeof(wled_metadata_t)) {
return false;
}
for (size_t offset = 0; offset <= dataSize - sizeof(wled_metadata_t); offset++) {
if ((binaryData[offset]) == static_cast<char>(WLED_CUSTOM_DESC_MAGIC)) {
// First byte matched; check next in an alignment-safe way
uint32_t data_magic;
memcpy(&data_magic, binaryData + offset, sizeof(data_magic));
// Check for magic number
if (data_magic == WLED_CUSTOM_DESC_MAGIC) {
wled_metadata_t candidate;
memcpy(&candidate, binaryData + offset, sizeof(candidate));
// Found potential match, validate version
if (candidate.desc_version != WLED_CUSTOM_DESC_VERSION) {
DEBUG_PRINTF_P(PSTR("Found WLED structure at offset %u but version mismatch: %u\n"),
offset, candidate.desc_version);
continue;
}
// Validate hash using runtime function
uint32_t expected_hash = djb2_hash_runtime(candidate.release_name);
if (candidate.hash != expected_hash) {
DEBUG_PRINTF_P(PSTR("Found WLED structure at offset %u but hash mismatch\n"), offset);
continue;
}
// Valid structure found - copy entire structure
*extractedDesc = candidate;
DEBUG_PRINTF_P(PSTR("Extracted WLED structure at offset %u: '%s'\n"),
offset, extractedDesc->release_name);
return true;
}
}
}
DEBUG_PRINTLN(F("No WLED custom description found in binary"));
return false;
}