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[superblock] Add defensive assert and bounds check

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The bound check condition should always be met because we selected `set_basic` as
our encoding type. But that code is very far away, so assert it is true so if it is
ever false we can catch it, and add a bounds check.

Fixes #2213.
This commit is contained in:
Nick Terrell 2020-06-22 10:21:38 -07:00
parent f03192c122
commit 1047097dad
1 changed files with 10 additions and 6 deletions
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16
lib/compress/zstd_compress_superblock.c
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@ -603,7 +603,7 @@ static size_t ZSTD_estimateSubBlockSize_symbolType(symbolEncodingType_e type,
const BYTE* codeTable, unsigned maxCode, const BYTE* codeTable, unsigned maxCode,
size_t nbSeq, const FSE_CTable* fseCTable, size_t nbSeq, const FSE_CTable* fseCTable,
const U32* additionalBits, const U32* additionalBits,
short const* defaultNorm, U32 defaultNormLog, short const* defaultNorm, U32 defaultNormLog, U32 defaultMax,
void* workspace, size_t wkspSize) void* workspace, size_t wkspSize)
{ {
unsigned* const countWksp = (unsigned*)workspace; unsigned* const countWksp = (unsigned*)workspace;
@ -615,7 +615,11 @@ static size_t ZSTD_estimateSubBlockSize_symbolType(symbolEncodingType_e type,
HIST_countFast_wksp(countWksp, &max, codeTable, nbSeq, workspace, wkspSize); /* can't fail */ HIST_countFast_wksp(countWksp, &max, codeTable, nbSeq, workspace, wkspSize); /* can't fail */
if (type == set_basic) { if (type == set_basic) {
cSymbolTypeSizeEstimateInBits = ZSTD_crossEntropyCost(defaultNorm, defaultNormLog, countWksp, max); /* We selected this encoding type, so it must be valid. */
assert(max <= defaultMax);
cSymbolTypeSizeEstimateInBits = max <= defaultMax
? ZSTD_crossEntropyCost(defaultNorm, defaultNormLog, countWksp, max)
: ERROR(GENERIC);
} else if (type == set_rle) { } else if (type == set_rle) {
cSymbolTypeSizeEstimateInBits = 0; cSymbolTypeSizeEstimateInBits = 0;
} else if (type == set_compressed || type == set_repeat) { } else if (type == set_compressed || type == set_repeat) {
@ -643,15 +647,15 @@ static size_t ZSTD_estimateSubBlockSize_sequences(const BYTE* ofCodeTable,
size_t cSeqSizeEstimate = 0; size_t cSeqSizeEstimate = 0;
cSeqSizeEstimate += ZSTD_estimateSubBlockSize_symbolType(fseMetadata->ofType, ofCodeTable, MaxOff, cSeqSizeEstimate += ZSTD_estimateSubBlockSize_symbolType(fseMetadata->ofType, ofCodeTable, MaxOff,
nbSeq, fseTables->offcodeCTable, NULL, nbSeq, fseTables->offcodeCTable, NULL,
OF_defaultNorm, OF_defaultNormLog, OF_defaultNorm, OF_defaultNormLog, DefaultMaxOff,
workspace, wkspSize); workspace, wkspSize);
cSeqSizeEstimate += ZSTD_estimateSubBlockSize_symbolType(fseMetadata->llType, llCodeTable, MaxLL, cSeqSizeEstimate += ZSTD_estimateSubBlockSize_symbolType(fseMetadata->llType, llCodeTable, MaxLL,
nbSeq, fseTables->litlengthCTable, LL_bits, nbSeq, fseTables->litlengthCTable, LL_bits,
LL_defaultNorm, LL_defaultNormLog, LL_defaultNorm, LL_defaultNormLog, MaxLL,
workspace, wkspSize); workspace, wkspSize);
cSeqSizeEstimate += ZSTD_estimateSubBlockSize_symbolType(fseMetadata->mlType, mlCodeTable, MaxML, cSeqSizeEstimate += ZSTD_estimateSubBlockSize_symbolType(fseMetadata->mlType, mlCodeTable, MaxML,
nbSeq, fseTables->matchlengthCTable, ML_bits, nbSeq, fseTables->matchlengthCTable, ML_bits,
ML_defaultNorm, ML_defaultNormLog, ML_defaultNorm, ML_defaultNormLog, MaxML,
workspace, wkspSize); workspace, wkspSize);
if (writeEntropy) cSeqSizeEstimate += fseMetadata->fseTablesSize; if (writeEntropy) cSeqSizeEstimate += fseMetadata->fseTablesSize;
return cSeqSizeEstimate + sequencesSectionHeaderSize; return cSeqSizeEstimate + sequencesSectionHeaderSize;
@ -809,7 +813,7 @@ static size_t ZSTD_compressSubBlock_multi(const seqStore_t* seqStorePtr,
if (sp < send) { if (sp < send) {
seqDef const* seq; seqDef const* seq;
repcodes_t rep; repcodes_t rep;
memcpy(&rep, prevCBlock->rep, sizeof(rep)); memcpy(&rep, prevCBlock->rep, sizeof(rep));
for (seq = sstart; seq < sp; ++seq) { for (seq = sstart; seq < sp; ++seq) {
rep = ZSTD_updateRep(rep.rep, seq->offset - 1, ZSTD_getSequenceLength(seqStorePtr, seq).litLength == 0); rep = ZSTD_updateRep(rep.rep, seq->offset - 1, ZSTD_getSequenceLength(seqStorePtr, seq).litLength == 0);
} }