Summary:

Using ExifInterface to call saveAttributes on a WebP file corrupts the WebP file, causing it to become invalid.

Steps to Reproduce:

Use ExifInterface to load a WebP file that does not contain a VP8X header. Call saveAttributes on the ExifInterface object. Attempt to open the resulting WebP file. Expected Result: The WebP file should remain valid and openable after saving attributes.

Actual Result: The WebP file becomes corrupted and cannot be opened properly.

Root Cause Analysis:

If the WebP file does not have a VP8X header, ExifInterface writes a new VP8X header.

When the WebP file's width or height is greater than 8191, the issue arises.

The following code causes the problem:

widthAndHeight = totalInputStream.readInt();
width = (widthAndHeight << 18) >> 18;
height = (widthAndHeight << 2) >> 18;

If the width or height is greater than 8191, left-shifting causes the sign bit to be lost, turning a '1' into a '0', which results in an incorrect width or height.

Environment

• Android version: Any version.
• Device model: Any device.
• ExifInterface version: 1.3.7