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C#: added a check in LZOvl.Support to make sure the 'compressed size' is correct (fits within the given file).

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barubary 2011-04-13 12:24:20 +00:00
parent 8d1a6abd9d
commit 426f89f37c
1 changed files with 11 additions and 2 deletions
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13
CSharp/DSDecmp/Formats/LZOvl.cs
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@ -6,7 +6,9 @@ namespace DSDecmp.Formats
{ {
/// <summary> /// <summary>
/// The LZ-Overlay compression format. Compresses part of the file from end to start. /// The LZ-Overlay compression format. Compresses part of the file from end to start.
/// Is used for the 'overlay' files in NDS games, as well as arm9.bin /// Is used for the 'overlay' files in NDS games, as well as arm9.bin.
/// Note that the last 12 bytes should not be included in the 'inLength' argument when
/// decompressing arm9.bin.
/// </summary> /// </summary>
public class LZOvl : CompressionFormat public class LZOvl : CompressionFormat
{ {
@ -37,7 +39,14 @@ namespace DSDecmp.Formats
byte headerLen = header[header.Length - 5]; byte headerLen = header[header.Length - 5];
if (inLength < headerLen) if (inLength < headerLen)
return false; return false;
// the compressed length is assumed to be valid.
// the compressed length should fit in the input file
int compressedLen = header[header.Length - 6] << 16
| header[header.Length - 7] << 8
| header[header.Length - 8];
if (compressedLen >= inLength - headerLen)
return false;
// verify that the rest of the header is filled with 0xFF // verify that the rest of the header is filled with 0xFF
for (int i = header.Length - 9; i >= header.Length - headerLen; i--) for (int i = header.Length - 9; i >= header.Length - headerLen; i--)
if (header[i] != 0xFF) if (header[i] != 0xFF)