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decompress: fix memory leak and size_t overflow in DDictHashSet_expand #4791

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decompress: fix memory leak and size_t overflow in DDictHashSet_expand #4791

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15 changes: 13 additions & 2 deletions lib/decompress/zstd_decompress.c
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Original file line number Diff line number Diff line change
Expand Up @@ -130,19 +130,30 @@ static size_t ZSTD_DDictHashSet_emplaceDDict(ZSTD_DDictHashSet* hashSet, const Z
*/
static size_t ZSTD_DDictHashSet_expand(ZSTD_DDictHashSet* hashSet, ZSTD_customMem customMem) {
size_t newTableSize = hashSet->ddictPtrTableSize * DDICT_HASHSET_RESIZE_FACTOR;
const ZSTD_DDict** newTable = (const ZSTD_DDict**)ZSTD_customCalloc(sizeof(ZSTD_DDict*) * newTableSize, customMem);
const ZSTD_DDict** newTable;
const ZSTD_DDict** oldTable = hashSet->ddictPtrTable;
size_t oldTableSize = hashSet->ddictPtrTableSize;
size_t i;

/* Guard against integer overflow: newTableSize must be strictly larger than the old size */
RETURN_ERROR_IF(newTableSize <= oldTableSize, memory_allocation, "DDict hash set size overflow on expand!");
newTable = (const ZSTD_DDict**)ZSTD_customCalloc(sizeof(ZSTD_DDict*) * newTableSize, customMem);

DEBUGLOG(4, "Expanding DDict hash table! Old size: %zu new size: %zu", oldTableSize, newTableSize);
RETURN_ERROR_IF(!newTable, memory_allocation, "Expanded hashset allocation failed!");
hashSet->ddictPtrTable = newTable;
hashSet->ddictPtrTableSize = newTableSize;
hashSet->ddictPtrCount = 0;
for (i = 0; i < oldTableSize; ++i) {
if (oldTable[i] != NULL) {
FORWARD_IF_ERROR(ZSTD_DDictHashSet_emplaceDDict(hashSet, oldTable[i]), "");
size_t const err = ZSTD_DDictHashSet_emplaceDDict(hashSet, oldTable[i]);
if (ZSTD_isError(err)) {
/* Free the old table before propagating the error to avoid a memory leak.
* The new table is already referenced by hashSet->ddictPtrTable and will
* be freed when the hashSet itself is freed. */
ZSTD_customFree((void*)oldTable, customMem);
return err;
}
}
}
ZSTD_customFree((void*)oldTable, customMem);
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