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Merge pull request #1135 from facebook/frameCSize 

decompress: changed error code when input is too large
dev
Yann Collet 2018-05-15 11:02:53 -07:00 committed by GitHub
parent b14c4bff96 d59cf02df0
commit 9938b17d4c
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GPG Key ID: 4AEE18F83AFDEB23
2 changed files with 25 additions and 8 deletions
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27
lib/decompress/zstd_decompress.c
View File

@ -1882,6 +1882,7 @@ static size_t ZSTD_decompressMultiFrame(ZSTD_DCtx* dctx,
const ZSTD_DDict* ddict) const ZSTD_DDict* ddict)
{ {
void* const dststart = dst; void* const dststart = dst;
int moreThan1Frame = 0;
assert(dict==NULL || ddict==NULL); /* either dict or ddict set, not both */ assert(dict==NULL || ddict==NULL); /* either dict or ddict set, not both */
if (ddict) { if (ddict) {
@ -1890,7 +1891,6 @@ static size_t ZSTD_decompressMultiFrame(ZSTD_DCtx* dctx,
} }
while (srcSize >= ZSTD_frameHeaderSize_prefix) { while (srcSize >= ZSTD_frameHeaderSize_prefix) {
U32 magicNumber;
#if defined(ZSTD_LEGACY_SUPPORT) && (ZSTD_LEGACY_SUPPORT >= 1) #if defined(ZSTD_LEGACY_SUPPORT) && (ZSTD_LEGACY_SUPPORT >= 1)
if (ZSTD_isLegacy(src, srcSize)) { if (ZSTD_isLegacy(src, srcSize)) {
@ -1912,10 +1912,9 @@ static size_t ZSTD_decompressMultiFrame(ZSTD_DCtx* dctx,
} }
#endif #endif
magicNumber = MEM_readLE32(src); { U32 const magicNumber = MEM_readLE32(src);
DEBUGLOG(4, "reading magic number %08X (expecting %08X)", DEBUGLOG(4, "reading magic number %08X (expecting %08X)",
(U32)magicNumber, (U32)ZSTD_MAGICNUMBER); (U32)magicNumber, (U32)ZSTD_MAGICNUMBER);
if (magicNumber != ZSTD_MAGICNUMBER) {
if ((magicNumber & 0xFFFFFFF0U) == ZSTD_MAGIC_SKIPPABLE_START) { if ((magicNumber & 0xFFFFFFF0U) == ZSTD_MAGIC_SKIPPABLE_START) {
size_t skippableSize; size_t skippableSize;
if (srcSize < ZSTD_skippableHeaderSize) if (srcSize < ZSTD_skippableHeaderSize)
@ -1927,9 +1926,7 @@ static size_t ZSTD_decompressMultiFrame(ZSTD_DCtx* dctx,
src = (const BYTE *)src + skippableSize; src = (const BYTE *)src + skippableSize;
srcSize -= skippableSize; srcSize -= skippableSize;
continue; continue;
} } }
return ERROR(prefix_unknown);
}
if (ddict) { if (ddict) {
/* we were called from ZSTD_decompress_usingDDict */ /* we were called from ZSTD_decompress_usingDDict */
@ -1943,11 +1940,25 @@ static size_t ZSTD_decompressMultiFrame(ZSTD_DCtx* dctx,
{ const size_t res = ZSTD_decompressFrame(dctx, dst, dstCapacity, { const size_t res = ZSTD_decompressFrame(dctx, dst, dstCapacity,
&src, &srcSize); &src, &srcSize);
if ( (ZSTD_getErrorCode(res) == ZSTD_error_prefix_unknown)
&& (moreThan1Frame==1) ) {
/* at least one frame successfully completed,
* but following bytes are garbage :
* it's more likely to be a srcSize error,
* specifying more bytes than compressed size of frame(s).
* This error message replaces ERROR(prefix_unknown),
* which would be confusing, as the first header is actually correct.
* Note that one could be unlucky, it might be a corruption error instead,
* happening right at the place where we expect zstd magic bytes.
* But this is _much_ less likely than a srcSize field error. */
return ERROR(srcSize_wrong);
}
if (ZSTD_isError(res)) return res; if (ZSTD_isError(res)) return res;
/* no need to bound check, ZSTD_decompressFrame already has */ /* no need to bound check, ZSTD_decompressFrame already has */
dst = (BYTE*)dst + res; dst = (BYTE*)dst + res;
dstCapacity -= res; dstCapacity -= res;
} }
moreThan1Frame = 1;
} /* while (srcSize >= ZSTD_frameHeaderSize_prefix) */ } /* while (srcSize >= ZSTD_frameHeaderSize_prefix) */
if (srcSize) return ERROR(srcSize_wrong); /* input not entirely consumed */ if (srcSize) return ERROR(srcSize_wrong); /* input not entirely consumed */

6
tests/fuzzer.c
View File

@ -375,6 +375,12 @@ static int basicUnitTests(U32 seed, double compressibility)
if (ZSTD_getErrorCode(r) != ZSTD_error_srcSize_wrong) goto _output_error; } if (ZSTD_getErrorCode(r) != ZSTD_error_srcSize_wrong) goto _output_error; }
DISPLAYLEVEL(3, "OK \n"); DISPLAYLEVEL(3, "OK \n");
DISPLAYLEVEL(3, "test%3i : decompress too large input : ", testNb++);
{ size_t const r = ZSTD_decompress(decodedBuffer, CNBuffSize, compressedBuffer, compressedBufferSize);
if (!ZSTD_isError(r)) goto _output_error;
if (ZSTD_getErrorCode(r) != ZSTD_error_srcSize_wrong) goto _output_error; }
DISPLAYLEVEL(3, "OK \n");
DISPLAYLEVEL(3, "test%3d : check CCtx size after compressing empty input : ", testNb++); DISPLAYLEVEL(3, "test%3d : check CCtx size after compressing empty input : ", testNb++);
{ ZSTD_CCtx* cctx = ZSTD_createCCtx(); { ZSTD_CCtx* cctx = ZSTD_createCCtx();
size_t const r = ZSTD_compressCCtx(cctx, compressedBuffer, compressedBufferSize, NULL, 0, 19); size_t const r = ZSTD_compressCCtx(cctx, compressedBuffer, compressedBufferSize, NULL, 0, 19);