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Merge pull request #510 from terrelln/bug-fix

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Fix input size validation edge cases
This commit is contained in:
Yann Collet 2018-04-23 15:28:19 -07:00 committed by GitHub
commit 57cc7daf22
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GPG Key ID: 4AEE18F83AFDEB23
2 changed files with 31 additions and 2 deletions
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8
lib/lz4.c
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@ -1520,6 +1520,7 @@ LZ4_FORCE_INLINE int LZ4_decompress_generic(
if ((partialDecoding) && (oexit > oend-MFLIMIT)) oexit = oend-MFLIMIT; /* targetOutputSize too high => just decode everything */
if ((endOnInput) && (unlikely(outputSize==0))) return ((srcSize==1) && (*ip==0)) ? 0 : -1; /* Empty output buffer */
if ((!endOnInput) && (unlikely(outputSize==0))) return (*ip==0?1:-1);
if ((endOnInput) && unlikely(srcSize==0)) return -1;
/* Main Loop : decode sequences */
while (1) {
@ -1529,11 +1530,13 @@ LZ4_FORCE_INLINE int LZ4_decompress_generic(
unsigned const token = *ip++;
assert(!endOnInput || ip <= iend); /* ip < iend before the increment */
/* shortcut for common case :
* in most circumstances, we expect to decode small matches (<= 18 bytes) separated by few literals (<= 14 bytes).
* this shortcut was tested on x86 and x64, where it improves decoding speed.
* it has not yet been benchmarked on ARM, Power, mips, etc. */
if (((ip + 14 /*maxLL*/ + 2 /*offset*/ <= iend)
* it has not yet been benchmarked on ARM, Power, mips, etc.
* NOTE: The loop begins with a read, so we must have one byte left at the end. */
if (((ip + 14 /*maxLL*/ + 2 /*offset*/ < iend)
& (op + 14 /*maxLL*/ + 18 /*maxML*/ <= oend))
& ((token < (15<<ML_BITS)) & ((token & ML_MASK) != 15)) ) {
size_t const ll = token >> ML_BITS;
@ -1553,6 +1556,7 @@ LZ4_FORCE_INLINE int LZ4_decompress_generic(
/* decode literal length */
if ((length=(token>>ML_BITS)) == RUN_MASK) {
unsigned s;
if (unlikely(endOnInput ? ip >= iend-RUN_MASK : 0)) goto _output_error; /* overflow detection */
do {
s = *ip++;
length += s;

25
tests/fuzzer.c
View File

@ -487,6 +487,31 @@ static int FUZ_test(U32 seed, U32 nbCycles, const U32 startCycle, const double c
ret = LZ4_decompress_fast(compressedBuffer, decodedBuffer, blockSize+1);
FUZ_CHECKTEST(ret>=0, "LZ4_decompress_fast should have failed, due to Output Size being too large");
/* Test decoding with empty input */
FUZ_DISPLAYTEST("LZ4_decompress_safe() with empty input");
LZ4_decompress_safe(NULL, decodedBuffer, 0, blockSize);
/* Test decoding with a one byte input */
FUZ_DISPLAYTEST("LZ4_decompress_safe() with one byte input");
{ char const tmp = 0xFF;
LZ4_decompress_safe(&tmp, decodedBuffer, 1, blockSize);
}
/* Test decoding shortcut edge case */
FUZ_DISPLAYTEST("LZ4_decompress_safe() with shortcut edge case");
{ char tmp[17];
/* 14 bytes of literals, followed by a 14 byte match.
* Should not read beyond the end of the buffer.
* See https://github.com/lz4/lz4/issues/508. */
*tmp = 0xEE;
memset(tmp + 1, 0, 14);
tmp[15] = 14;
tmp[16] = 0;
ret = LZ4_decompress_safe(tmp, decodedBuffer, sizeof(tmp), blockSize);
FUZ_CHECKTEST(ret >= 0, "LZ4_decompress_safe() should fail");
}
/* Test decoding with output size exactly what's necessary => must work */
FUZ_DISPLAYTEST();
decodedBuffer[blockSize] = 0;