ddidderr/zstd-rs
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[legacy] Fix ZSTDv0*_decodeSequence()

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* Version <= 0.5 could read beyond the end of `dumps`, which points into
  the input buffer.
* Check the validity of `dumps` before using it, if it is out of bounds
  return garbage values. There is no return code for this function.
* Introduce `MEM_readLE24()` for simplicity, since I don't want to trust
  that there is an extra byte after `dumps`.
This commit is contained in:
Nick Terrell
2019-04-19 11:34:52 -07:00
parent 9ad7ea44ec
commit 0fd322f812
5 changed files with 50 additions and 43 deletions
Download Patch File Download Diff File Expand all files Collapse all files
lib/legacy/zstd_v01.c
+6 -15
View File
@@ -1358,8 +1358,6 @@ static unsigned ZSTD_isLittleEndian(void)
static U16 ZSTD_read16(const void* p) { U16 r; memcpy(&r, p, sizeof(r)); return r; }
static U32 ZSTD_read32(const void* p) { U32 r; memcpy(&r, p, sizeof(r)); return r; }
static void ZSTD_copy4(void* dst, const void* src) { memcpy(dst, src, 4); }
static void ZSTD_copy8(void* dst, const void* src) { memcpy(dst, src, 8); }
@@ -1384,16 +1382,9 @@ static U16 ZSTD_readLE16(const void* memPtr)
}
}
static U32 ZSTD_readLE32(const void* memPtr)
static U32 ZSTD_readLE24(const void* memPtr)
{
if (ZSTD_isLittleEndian())
return ZSTD_read32(memPtr);
else
{
const BYTE* p = (const BYTE*)memPtr;
return (U32)((U32)p[0] + ((U32)p[1]<<8) + ((U32)p[2]<<16) + ((U32)p[3]<<24));
}
return ZSTD_readLE16(memPtr) + (((const BYTE*)memPtr)[2] << 16);
}
static U32 ZSTD_readBE32(const void* memPtr)
@@ -1707,13 +1698,13 @@ static void ZSTD_decodeSequence(seq_t* seq, seqState_t* seqState)
seqState->prevOffset = seq->offset;
if (litLength == MaxLL)
{
U32 add = dumps<de ? *dumps++ : 0;
const U32 add = dumps<de ? *dumps++ : 0;
if (add < 255) litLength += add;
else
{
if (dumps<=(de-3))
{
litLength = ZSTD_readLE32(dumps) & 0xFFFFFF; /* no pb : dumps is always followed by seq tables > 1 byte */
litLength = ZSTD_readLE24(dumps);
dumps += 3;
}
}
@@ -1735,13 +1726,13 @@ static void ZSTD_decodeSequence(seq_t* seq, seqState_t* seqState)
matchLength = FSE_decodeSymbol(&(seqState->stateML), &(seqState->DStream));
if (matchLength == MaxML)
{
U32 add = dumps<de ? *dumps++ : 0;
const U32 add = dumps<de ? *dumps++ : 0;
if (add < 255) matchLength += add;
else
{
if (dumps<=(de-3))
{
matchLength = ZSTD_readLE32(dumps) & 0xFFFFFF; /* no pb : dumps is always followed by seq tables > 1 byte */
matchLength = ZSTD_readLE24(dumps);
dumps += 3;
}
}