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libwebm: handle underflow from IMkvReader::Read

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Change-Id: I8bb0ed53b7bfdde6c0ed24665591f95d7cf43083
This commit is contained in:
matthewjheaney 2011-02-10 20:42:52 -05:00
parent a1736157be
commit d82f86a40a
1 changed files with 13 additions and 5 deletions
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18
mkvparser.cpp
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@ -40,11 +40,13 @@ long long mkvparser::ReadUInt(IMkvReader* pReader, long long pos, long& len)
assert((available - pos) >= 1); //assume here max u-int len is 8
#endif
len = 1;
unsigned char b;
status = pReader->Read(pos, 1, &b);
if (status < 0) //error
if (status < 0) //error or underflow
return status;
if (status > 0) //interpreted as "underflow"
@ -54,7 +56,6 @@ long long mkvparser::ReadUInt(IMkvReader* pReader, long long pos, long& len)
return E_FILE_FORMAT_INVALID;
unsigned char m = 0x80;
len = 1;
while (!(b & m))
{
@ -74,10 +75,16 @@ long long mkvparser::ReadUInt(IMkvReader* pReader, long long pos, long& len)
status = pReader->Read(pos, 1, &b);
if (status < 0)
{
len = 1;
return status;
}
if (status > 0)
{
len = 1;
return E_BUFFER_NOT_FULL;
}
result <<= 8;
result |= b;
@ -105,6 +112,8 @@ long long mkvparser::GetUIntLength(
if (pos >= available)
return pos; //too few bytes available
len = 1;
unsigned char b;
status = pReader->Read(pos, 1, &b);
@ -118,7 +127,6 @@ long long mkvparser::GetUIntLength(
return E_FILE_FORMAT_INVALID;
unsigned char m = 0x80;
len = 1;
while (!(b & m))
{
@ -5186,10 +5194,10 @@ long Cluster::LoadBlockEntries(long long& pos, long& len) const
long long result = GetUIntLength(pReader, pos, len);
if (result < 0) //error
if (result < 0) //error or underflow
return static_cast<long>(result);
if (result > 0) //weird
if (result > 0) //underflow (weird)
{
len = 1;
return E_BUFFER_NOT_FULL;