ArrayIndexOutOfBoundsException when reading FatFile found in ClusterChain.kt:157

[cybex-dev]

Hi

Came across a ArrayIndexOutOfBoundsException - the specifics around the exception eludes me at the moment as I saw this in a Firebase crash report.

I will try and update this with all the information I can once I am able to replicate the issue, but for the moment I want to post this here and bring it to your attention.

Problem

Could not read valid USB file correctly

Expected behavior

Read valid USBFile in its entirety

Actual behavior

Failed to read file, exact cause unknown

Stacktrace of Exception

Fatal Exception: java.lang.ArrayIndexOutOfBoundsException: length=1; index=1 at com.github.mjdev.libaums.fs.fat32.ClusterChain.read$libaums_release(ClusterChain.kt:157) at com.github.mjdev.libaums.fs.fat32.FatFile.read(FatFile.kt:104) at com.github.mjdev.libaums.fs.UsbFileInputStream.read(UsbFileInputStream.kt:79) at com.company.example.libs.FATUtils.copyFrom(FATUtils.java:107) at com.company.example.libs.FATUtils.copyFrom(FATUtils.java:59) at com.company.example.activites.LoadingActivity$1.onMassStorageReady(LoadingActivity.java:113) at com.company.example.libs.StorageUtils.onMassStorageReady(StorageUtils.java:314) at com.company.example.libs.StorageUtils.getUsableUSBMassStorageDevice(StorageUtils.java:133) at com.company.example.activites.LoadingActivity.lambda$onCreate$0$LoadingActivity(LoadingActivity.java:169) at com.company.example.activites.-$$Lambda$LoadingActivity$Kc3ikVBqpggN1SSjCNjFbwHs4Jk.run(:2) at java.lang.Thread.run(Thread.java:919)

Code where problem occurs

// Get file and check if correct file based on path
UsbFile usbFile= cd(srcFileSystem.getRootDirectory(), srcUsbFilePath);
if (!usbFile.getAbsolutePath().equals(srcUsbFilePath)) {
        // Incorrect file, handle appropriately
	Log.e(TAG, "copyFrom: File " + srcUsbFilePath + " does not exist");
	if (copyListener != null)
		copyListener.onCopyError("File " + srcUsbFilePath + " does not exist");
	return FileUtils.FileStatus.NotFound;
}

// Proceed to read file
//...
InputStream inputStream = new UsbFileInputStream(usbFile);
try {
	long fileLength = usbFile.getLength();
	while ((count = inputStream.read(bytes)) != -1) {          **// Offending line @ FATUtils.java:107 - see Stacktrace**
		out.write(bytes, 0, count);
		total += count;
		if (copyListener != null)
			copyListener.onCopyProgress(total, fileLength);
	}
} catch (IOException e) {
	e.printStackTrace();
	Log.e(TAG, "copyFrom: An IO Error occurred while copying file");
	if (copyListener != null)
		copyListener.onCopyError("An IO Error occurred while copying file");
	return FileUtils.FileStatus.IOError;
}

[magnusja]

Hey there,

can you maybe link the firebase report? Does it has anything to do with this library?

I remember that someone already reported this a while back but I thought we fixed this ..

[kuza2010]

Hey there,

In one part my application during read operation I get an issue like that above.

JNI DETECTED ERROR IN APPLICATION: JNI NewByteArray called with pending exception java.lang.ArrayIndexOutOfBoundsException: length=1; index=1
2020-02-19 12:40:00.080 31459-31642/com.my.app A/zygote64: java_vm_ext.cc:504] at void com.github.mjdev.libaums.fs.fat32.ClusterChain.read$libaums_release(long, java.nio.ByteBuffer) (ClusterChain.kt:157)
2020-02-19 12:40:00.080 31459-31642/com.my.app A/zygote64: java_vm_ext.cc:504] at void com.github.mjdev.libaums.fs.fat32.FatFile.read(long, java.nio.ByteBuffer) (FatFile.kt:104)
2020-02-19 12:40:00.080 31459-31642/com.my.app A/zygote64: java_vm_ext.cc:504] at int com.sandisk.everest.fs.libaums.UsbInputStream.read(byte[], int, int) (UsbInputStream.java:38)

[magnusja]

Hmm that is bad. Can you log what with what offset/length you are calling the read method?

[cybex-dev]

hi @magnusja

this feels like a useless comment but I will say it in anycase.

I think my issue appeared when attempting to read an incomplete file. (I copied over a file but it did not complete, which was the file I was trying to read). I doubt this makes any difference, I have not yet come across this issue again as the original problem occurred during development. If I find anything else, I will post an update.

[kuza2010]

hi @magnusja

So, I investigate what went wrong in my case. The issue appears after https://github.com/magnusja/libaums/issues/237 In one part of my app I used a secret store to keep some files in encrypted. It seems, that some system information uncompleted for the secret store when it is closing (https://github.com/magnusja/libaums/issues/237 appear during copying process). And after that, when I try to open the secret store I got the ArrayIndexOutOfBoundsException.

If I find anything that can help, I will post an update.

[magnusja]

Hey,

so this is then a follow up error of the first error. If writing is unsuccessful then the cluster chain has no end indicator.

[cybex-dev]

@magnusja Hi Magnus

So it seems I have gotten a number of additional crashes, however these have a different output to that shown above.

Instead of

Fatal Exception: java.lang.ArrayIndexOutOfBoundsException: length=1; index=1

I show a number of crashes with the following Stack Trace

Fatal Exception: java.lang.ArrayIndexOutOfBoundsException: length=0; index=0 at com.github.mjdev.libaums.fs.fat32.ClusterChain.read$libaums_release(ClusterChain.kt:157) at com.github.mjdev.libaums.fs.fat32.FatFile.read(FatFile.kt:104) at com.github.mjdev.libaums.fs.UsbFileInputStream.read(UsbFileInputStream.kt:79)

I have added additional logging to try and get some information. Would any additional info from my side assist you in resolving this problem?

[magnusja]

Well this crash is probably because of an interrupted write to a cluster chain. What do you think is the best way to handle this? Check the length and return zero bytes?

[magnusja]

Fixed with v0.9.4