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Add checks to avoid overreading supplied buffers and fix issue #61.

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This commit is contained in:
Robert Kausch 2017-04-23 21:31:36 +02:00
parent 5eb6f0db8c
commit 6b0d8201b1
2 changed files with 45 additions and 20 deletions
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47
libFDK/include/FDK_bitstream.h
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@ -212,9 +212,20 @@ FDK_INLINE UINT FDKreadBits(HANDLE_FDK_BITSTREAM hBitStream,
INT missingBits = numberOfBits - hBitStream->BitsInCache;
if (missingBits > 0)
{
UINT bits = hBitStream->CacheWord << missingBits;
hBitStream->CacheWord = FDK_get32 (&hBitStream->hBitBuf) ;
hBitStream->BitsInCache = CACHE_BITS - missingBits;
const UINT bits = hBitStream->CacheWord << missingBits;
const UINT validBits = FDK_getValidBits (&hBitStream->hBitBuf);
if (validBits >= 32)
{
hBitStream->CacheWord = FDK_get32 (&hBitStream->hBitBuf) ;
hBitStream->BitsInCache = CACHE_BITS - missingBits;
}
else
{
hBitStream->CacheWord = FDK_get (&hBitStream->hBitBuf,validBits) ;
hBitStream->BitsInCache = validBits - missingBits;
}
return ( bits | (hBitStream->CacheWord >> hBitStream->BitsInCache)) & BitMask[numberOfBits];
}
@ -226,10 +237,12 @@ FDK_INLINE UINT FDKreadBits(HANDLE_FDK_BITSTREAM hBitStream,
if (hBitStream->BitsInCache <= numberOfBits)
{
const INT freeBits = (CACHE_BITS-1) - hBitStream->BitsInCache ;
const UINT validBits = FDK_getValidBits (&hBitStream->hBitBuf) ;
const INT freeBits = (CACHE_BITS-1) - hBitStream->BitsInCache ;
const INT bitsToRead = (freeBits <= validBits) ? freeBits : validBits ;
hBitStream->CacheWord = (hBitStream->CacheWord << freeBits) | FDK_get (&hBitStream->hBitBuf,freeBits) ;
hBitStream->BitsInCache += freeBits ;
hBitStream->CacheWord = (hBitStream->CacheWord << bitsToRead) | FDK_get (&hBitStream->hBitBuf,bitsToRead) ;
hBitStream->BitsInCache += bitsToRead ;
}
hBitStream->BitsInCache -= numberOfBits ;
@ -243,8 +256,18 @@ FDK_INLINE UINT FDKreadBit(HANDLE_FDK_BITSTREAM hBitStream)
#ifdef OPTIMIZE_FDKREADBITS
if (!hBitStream->BitsInCache)
{
hBitStream->CacheWord = FDK_get32 (&hBitStream->hBitBuf);
hBitStream->BitsInCache = CACHE_BITS;
const UINT validBits = FDK_getValidBits (&hBitStream->hBitBuf);
if (validBits >= 32)
{
hBitStream->CacheWord = FDK_get32 (&hBitStream->hBitBuf);
hBitStream->BitsInCache = CACHE_BITS;
}
else
{
hBitStream->CacheWord = FDK_get (&hBitStream->hBitBuf,validBits);
hBitStream->BitsInCache = validBits;
}
}
hBitStream->BitsInCache--;
@ -268,10 +291,12 @@ inline UINT FDKread2Bits(HANDLE_FDK_BITSTREAM hBitStream)
UINT BitsInCache = hBitStream->BitsInCache;
if (BitsInCache < 2) /* Comparison changed from 'less-equal' to 'less' */
{
const INT freeBits = (CACHE_BITS-1) - BitsInCache ;
const UINT validBits = FDK_getValidBits (&hBitStream->hBitBuf) ;
const INT freeBits = (CACHE_BITS-1) - BitsInCache ;
const INT bitsToRead = (freeBits <= validBits) ? freeBits : validBits ;
hBitStream->CacheWord = (hBitStream->CacheWord << freeBits) | FDK_get (&hBitStream->hBitBuf,freeBits) ;
BitsInCache += freeBits;
hBitStream->CacheWord = (hBitStream->CacheWord << bitsToRead) | FDK_get (&hBitStream->hBitBuf,bitsToRead) ;
BitsInCache += bitsToRead;
}
hBitStream->BitsInCache = BitsInCache - 2;
return (hBitStream->CacheWord >> hBitStream->BitsInCache) & 0x3;

18
libFDK/src/FDK_bitbuffer.cpp
View File

@ -157,6 +157,8 @@ void FDK_ResetBitBuffer ( HANDLE_FDK_BITBUF hBitBuf )
INT FDK_get (HANDLE_FDK_BITBUF hBitBuf, const UINT numberOfBits)
{
if (numberOfBits == 0 || numberOfBits > hBitBuf->ValidBits) return 0;
UINT byteOffset = hBitBuf->BitNdx >> 3 ;
UINT bitOffset = hBitBuf->BitNdx & 0x07 ;
@ -166,22 +168,20 @@ INT FDK_get (HANDLE_FDK_BITBUF hBitBuf, const UINT numberOfBits)
UINT byteMask = hBitBuf->bufSize - 1 ;
UINT tx = (hBitBuf->Buffer [ byteOffset & byteMask] << 24) |
(hBitBuf->Buffer [(byteOffset+1) & byteMask] << 16) |
(hBitBuf->Buffer [(byteOffset+2) & byteMask] << 8) |
hBitBuf->Buffer [(byteOffset+3) & byteMask];
UINT tx = hBitBuf->Buffer [ byteOffset & byteMask] << 24 << bitOffset;
if (bitOffset)
{
tx <<= bitOffset;
tx |= hBitBuf->Buffer [(byteOffset+4) & byteMask] >> (8-bitOffset);
}
if (numberOfBits + bitOffset > 8) tx |= hBitBuf->Buffer [(byteOffset+1) & byteMask] << 16 << bitOffset;
if (numberOfBits + bitOffset > 16) tx |= hBitBuf->Buffer [(byteOffset+2) & byteMask] << 8 << bitOffset;
if (numberOfBits + bitOffset > 24) tx |= hBitBuf->Buffer [(byteOffset+3) & byteMask] << bitOffset;
if (numberOfBits + bitOffset > 32) tx |= hBitBuf->Buffer [(byteOffset+4) & byteMask] >> (8 - bitOffset);
return (tx >> (32 - numberOfBits)) ;
}
INT FDK_get32 (HANDLE_FDK_BITBUF hBitBuf)
{
if (hBitBuf->ValidBits < 32) return 0;
UINT BitNdx = hBitBuf->BitNdx + 32;
if (BitNdx <= hBitBuf->bufBits)
{