[iOS] Image.compress (manual) crashes the app in Release builds (vImageScale_ARGB8888 use-after-free) and on unreadable images #430

Title: [iOS] Image.compress (manual) crashes the app in Release builds (vImageScale_ARGB8888 use-after-free) and on unreadable images

Current behavior

Image.compress(uri, { compressionMethod: 'manual', maxWidth, maxHeight, quality }) crashes the whole app on iOS in two cases. Both are in ios/Image/ImageCompressor.swift and are unchanged in 2.0.4.

1. Release builds crash while resizing (EXC_BAD_ACCESS)

EXC_BAD_ACCESS
vVertical_Scale_ARGB_8888_Accelerate
vImageScale_ARGB8888
ImageCompressor.manualResize(_:maxWidth:maxHeight:)

manualResize passes &sourceData / &targetData (Swift [UInt8] arrays) into CGContext(data:) and vImage_Buffer(data:). A pointer from &array is only valid for the duration of the call that receives it. With -O, Swift can release sourceData before vImageScale_ARGB8888 reads it, so vImage reads freed memory. Debug builds keep the array alive longer, which is why this only shows up in App Store / TestFlight builds.

Related issues in the same function:

• free(&targetData) is called on Swift-managed memory (undefined behaviour).
• targetRef! is force-unwrapped.
• The source size is taken from image.size (points) instead of cgImage.width / cgImage.height (pixels).

2. A missing or unreadable image terminates the app instead of rejecting

When loadImage returns nil, manualCompressHandler (and autoCompressHandler) call NSException(...).raise(). Swift's do/catch in ImageMain.image_compress can't catch an Objective-C exception, so the app aborts. writeImage and copyExifInfo also crash on failure through force unwraps:

• jpegData(...)! and pngData()!
• image.cgImage!
• CGImageSourceCreateWithURL(...)!
• CGImageDestinationCreateWithData(...)!

3. (Minor) Some images come out stretched and sideways

scaleAndRotateImage creates its CGContext with the source's bitsPerComponent and bitmapInfo. For 16-bit PNG, PNG with alpha and 10-bit HEIC, that context fails to create, so the function returns the unrotated image. manualResize then scales it to the rotated dimensions, which stretches it.

Expected behavior

• Resizing works in Release builds without memory errors.
• A missing, corrupt or unsupported image rejects the promise with an error instead of crashing the app.
• Images with an EXIF orientation come out upright and correctly proportioned, whatever their pixel format.

Suggested fixes (we have these working in a local patch and can open a PR):

• Resize with vImage-owned buffers (vImage_Buffer(cgImage:) → vImageScale_ARGB8888 → vImageCreateCGImageFromBuffer). This also lowers peak memory for a 12 MP photo from about 150 MB to about 60 MB.
• Make the handlers throws and replace raise() and ! with Swift errors, so that image_compress calls reject(...).
• In scaleAndRotateImage, retry with an 8-bit sRGB context when the source-format context can't be created.

Platform

• Android
• iOS

React Native Version

0.87.1 (New Architecture, react-native-nitro-modules 0.37.1)

React Native Compressor Version

2.0.3 (the iOS image code is unchanged in 2.0.4)

Reproducible Steps And Demo

Crash 1: resize in a Release build

1. Build the app in the Release configuration (TestFlight / App Store, or Release on a device or simulator).
2. Take or pick a 12 MP or 48 MP photo with the camera.
3. Call:

   await Image.compress(photoUri, {
     compressionMethod: 'manual',
     maxWidth: 1080,
     maxHeight: 1920,
     quality: 0.9,
   });

4. The app crashes intermittently with EXC_BAD_ACCESS in vVertical_Scale_ARGB_8888_Accelerate. We saw it in production on an iPhone 11 running iOS 27.0.1. The same code never crashes in Debug.

You can also reproduce it outside React Native: compile manualResize on its own with swiftc -O, resize a 12 MP image, and it crashes at the same frame. With -Onone, it doesn't.

Crash 2: missing or unreadable image

1. Any build configuration.
2. Call:

   await Image.compress('file:///path/that/does/not/exist.jpg', {
     compressionMethod: 'manual',
   });

   You can also pass a truncated JPEG instead.
3. The app aborts with an uncaught NSException (unsupported_value) instead of the promise rejecting.

Issue 3: stretched, sideways image

1. Create a 16-bit PNG, or a PNG with alpha, tagged with EXIF Orientation 6.
2. Compress it with the options from crash 1.
3. The output is stretched and rotated 90°.