2 Commits

2 changed files with 12 additions and 4 deletions

View File

@@ -20,7 +20,7 @@ public class PngHdr
stream.ReadExactly(buffer[..8]); stream.ReadExactly(buffer[..8]);
uint ihdrLength = BitConverter.ToUInt32(buffer); uint ihdrLength = ReadBigEndianUInt32(buffer[..4]);
// The next four bytes will be the length of the IHDR section (it should be 13 bytes but we only need 8) // The next four bytes will be the length of the IHDR section (it should be 13 bytes but we only need 8)
if (ihdrLength < 8) if (ihdrLength < 8)
@@ -32,8 +32,8 @@ public class PngHdr
stream.ReadExactly(buffer[..8]); stream.ReadExactly(buffer[..8]);
uint width = BitConverter.ToUInt32(buffer); uint width = ReadBigEndianUInt32(buffer[..4]);
uint height = BitConverter.ToUInt32(buffer[4..]); uint height = ReadBigEndianUInt32(buffer[4..8]);
// Validate the width/height are non-negative and... that's all we care about! // Validate the width/height are non-negative and... that's all we care about!
if (width > int.MaxValue || height > int.MaxValue) if (width > int.MaxValue || height > int.MaxValue)
@@ -46,4 +46,12 @@ public class PngHdr
return InvalidSize; return InvalidSize;
} }
} }
} // Minimal helper for big-endian conversion
private static uint ReadBigEndianUInt32(ReadOnlySpan<byte> bytes)
{
return ((uint)bytes[0] << 24) |
((uint)bytes[1] << 16) |
((uint)bytes[2] << 8) |
bytes[3];
}
}

View File