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Enforce literal buffer capacity contract #4782

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Enforce literal buffer capacity contract #4782

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2 changes: 1 addition & 1 deletion lib/compress/zstd_compress.c
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Original file line number Diff line number Diff line change
Expand Up @@ -8125,7 +8125,7 @@ ZSTD_compressSequencesAndLiterals(ZSTD_CCtx* cctx,
/* Transparent initialization stage, same as compressStream2() */
DEBUGLOG(4, "ZSTD_compressSequencesAndLiterals (dstCapacity=%zu)", dstCapacity);
assert(cctx != NULL);
if (litCapacity < litSize) {
if (litCapacity < litSize || litCapacity - litSize < 8) {
RETURN_ERROR(workSpace_tooSmall, "literals buffer is not large enough: must be at least 8 bytes larger than litSize (risk of read out-of-bound)");
}
FORWARD_IF_ERROR(ZSTD_CCtx_init_compressStream2(cctx, ZSTD_e_end, decompressedSize), "CCtx initialization failed");
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9 changes: 8 additions & 1 deletion tests/fuzzer.c
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Original file line number Diff line number Diff line change
Expand Up @@ -4476,6 +4476,13 @@ static int basicUnitTests(U32 const seed, double compressibility)
{ size_t const litSize = FUZ_getLitSize(seqs, nbSeqs);
FUZ_transferLiterals(litBuffer, decompressSize, CNBuffer, srcSize, seqs, nbSeqs);

/* literal buffer capacity without 8 bytes of margin: must fail */
compressedSize = ZSTD_compressSequencesAndLiterals(cctx, dst, dstCapacity, seqs, nbSeqs, litBuffer, litSize, litSize+7, srcSize);
if (ZSTD_getErrorCode(compressedSize) != ZSTD_error_workSpace_tooSmall) {
DISPLAY("ZSTD_compressSequencesAndLiterals() should have failed: literals buffer capacity is too small\n");
goto _output_error;
}

/* not enough literals: must fail */
compressedSize = ZSTD_compressSequencesAndLiterals(cctx, dst, dstCapacity, seqs, nbSeqs, src, litSize-1, decompressSize, srcSize);
if (!ZSTD_isError(compressedSize)) {
Expand Down Expand Up @@ -4505,7 +4512,7 @@ static int basicUnitTests(U32 const seed, double compressibility)
}

/* correct amount of literals: should compress successfully */
compressedSize = ZSTD_compressSequencesAndLiterals(cctx, dst, dstCapacity, seqs, nbSeqs, litBuffer, litSize, decompressSize, srcSize);
compressedSize = ZSTD_compressSequencesAndLiterals(cctx, dst, dstCapacity, seqs, nbSeqs, litBuffer, litSize, litSize+8, srcSize);
if (ZSTD_isError(compressedSize)) {
DISPLAY("Error in ZSTD_compressSequencesAndLiterals()\n");
goto _output_error;
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