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[decompress] Fix nullptr addition & improve fuzzer #3356

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Merged
terrelln merged 1 commit into from
Dec 15, 2022
Merged

[decompress] Fix nullptr addition & improve fuzzer #3356

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9 changes: 7 additions & 2 deletions lib/decompress/zstd_decompress.c
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Original file line number Diff line number Diff line change
Expand Up @@ -2058,6 +2058,7 @@ size_t ZSTD_decompressStream(ZSTD_DStream* zds, ZSTD_outBuffer* output, ZSTD_inB
size_t const decompressedSize = ZSTD_decompress_usingDDict(zds, op, (size_t)(oend-op), istart, cSize, ZSTD_getDDict(zds));
if (ZSTD_isError(decompressedSize)) return decompressedSize;
DEBUGLOG(4, "shortcut to single-pass ZSTD_decompress_usingDDict()")
assert(istart != NULL);
ip = istart + cSize;
op = op ? op + decompressedSize : op; /* can occur if frameContentSize = 0 (empty frame) */
zds->expected = 0;
Expand Down Expand Up @@ -2143,6 +2144,7 @@ size_t ZSTD_decompressStream(ZSTD_DStream* zds, ZSTD_outBuffer* output, ZSTD_inB
}
if ((size_t)(iend-ip) >= neededInSize) { /* decode directly from src */
FORWARD_IF_ERROR(ZSTD_decompressContinueStream(zds, &op, oend, ip, neededInSize), "");
assert(ip != NULL);
ip += neededInSize;
/* Function modifies the stage so we must break */
break;
Expand All @@ -2166,8 +2168,11 @@ size_t ZSTD_decompressStream(ZSTD_DStream* zds, ZSTD_outBuffer* output, ZSTD_inB
"should never happen");
loadedSize = ZSTD_limitCopy(zds->inBuff + zds->inPos, toLoad, ip, (size_t)(iend-ip));
}
ip += loadedSize;
zds->inPos += loadedSize;
if (loadedSize != 0) {
/* ip may be NULL */
ip += loadedSize;
zds->inPos += loadedSize;
}
if (loadedSize < toLoad) { someMoreWork = 0; break; } /* not enough input, wait for more */

/* decode loaded input */
Expand Down
3 changes: 2 additions & 1 deletion lib/legacy/zstd_v06.c
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Expand Up @@ -4029,7 +4029,8 @@ size_t ZBUFFv06_decompressContinue(ZBUFFv06_DCtx* zbd,
size_t const toLoad = hSize - zbd->lhSize; /* if hSize!=0, hSize > zbd->lhSize */
if (ZSTDv06_isError(hSize)) return hSize;
if (toLoad > (size_t)(iend-ip)) { /* not enough input to load full header */
memcpy(zbd->headerBuffer + zbd->lhSize, ip, iend-ip);
if (ip != NULL)
memcpy(zbd->headerBuffer + zbd->lhSize, ip, iend-ip);
zbd->lhSize += iend-ip;
*dstCapacityPtr = 0;
return (hSize - zbd->lhSize) + ZSTDv06_blockHeaderSize; /* remaining header bytes + next block header */
Expand Down
3 changes: 2 additions & 1 deletion lib/legacy/zstd_v07.c
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Expand Up @@ -4411,7 +4411,8 @@ size_t ZBUFFv07_decompressContinue(ZBUFFv07_DCtx* zbd,
if (hSize != 0) {
size_t const toLoad = hSize - zbd->lhSize; /* if hSize!=0, hSize > zbd->lhSize */
if (toLoad > (size_t)(iend-ip)) { /* not enough input to load full header */
memcpy(zbd->headerBuffer + zbd->lhSize, ip, iend-ip);
if (ip != NULL)
memcpy(zbd->headerBuffer + zbd->lhSize, ip, iend-ip);
zbd->lhSize += iend-ip;
*dstCapacityPtr = 0;
return (hSize - zbd->lhSize) + ZSTDv07_blockHeaderSize; /* remaining header bytes + next block header */
Expand Down
8 changes: 4 additions & 4 deletions tests/fuzz/stream_decompress.c
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Expand Up @@ -99,14 +99,14 @@ int LLVMFuzzerTestOneInput(const uint8_t *src, size_t size)

while (size > 0) {
ZSTD_inBuffer in = makeInBuffer(&src, &size, producer);
while (in.pos != in.size) {
do {
size_t const rc = ZSTD_decompressStream(dstream, &out, &in);
if (ZSTD_isError(rc)) goto error;
if (out.pos == out.size) {
if (stableOutBuffer) goto error;
out = makeOutBuffer(producer, buf, bufSize);
}
size_t const rc = ZSTD_decompressStream(dstream, &out, &in);
if (ZSTD_isError(rc)) goto error;
}
} while (in.pos != in.size);
}

error:
Expand Down