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mkvparser: Handle invalid lengths and rollover in ParseElementHeader().

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BUG=23224239

Change-Id: I597054dc552b54f99a6716fb8f1b0f2480f2a29b
This commit is contained in:
Tom Finegan 2015-08-19 12:23:21 -07:00
parent cd96a76985
commit f250aceeaa
1 changed files with 16 additions and 5 deletions
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21
mkvparser.cpp
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@ -289,31 +289,42 @@ long mkvparser::UnserializeString(IMkvReader* pReader, long long pos,
long mkvparser::ParseElementHeader(IMkvReader* pReader, long long& pos,
long long stop, long long& id,
long long& size) {
if ((stop >= 0) && (pos >= stop))
if (stop >= 0 && pos >= stop)
return E_FILE_FORMAT_INVALID;
long len;
id = ReadUInt(pReader, pos, len);
if (id < 0)
if (id < 0 || len < 1 || len > 4)
// An ID must be at least 1 byte long, and cannot exceed 4.
// See EBMLMaxIDLength: http://www.matroska.org/technical/specs/index.html
return E_FILE_FORMAT_INVALID;
pos += len; // consume id
if ((stop >= 0) && (pos >= stop))
if (stop >= 0 && pos >= stop)
return E_FILE_FORMAT_INVALID;
size = ReadUInt(pReader, pos, len);
if (size < 0)
if (size < 0 || len < 1 || len > 8) {
// Invalid: Negative payload size, negative or 0 length integer, or integer
// larger than 64 bits (libwebm cannot handle them).
return E_FILE_FORMAT_INVALID;
}
// Avoid rolling over pos when very close to LONG_LONG_MAX.
const unsigned long long rollover_check =
static_cast<unsigned long long>(pos) + len;
if (rollover_check > LONG_LONG_MAX)
return E_FILE_FORMAT_INVALID;
pos += len; // consume length of size
// pos now designates payload
if ((stop >= 0) && ((pos + size) > stop))
if (stop >= 0 && pos >= stop)
return E_FILE_FORMAT_INVALID;
return 0; // success