SIGBUS Crash in Native Signature Library (nSign) on ARM64-v8a using Android App Bundles (AAB) v5.4.x

[sebastianpeya]

Hello Adjust Team,

We are experiencing a critical, low-volume native crash (SIGBUS) that appeared after migrating our Android application from Adjust SDK v4.x to v5.4.0, and which persists after updating to v5.4.1.

Problem Description
The application is randomly crashing on a small percentage of our user base (approx. 200 users, out of millions), exclusively within the native code of the Adjust SDK's signature library.

Crash Details (Sentry Report)
The exception consistently points to a Bus Error (SIGBUS) within the native helper function responsible for signing:

Exception Type: SIGBUS: BusError

Function at Fault: Java_com_adjust_sdk_sig_NativeLibHelper_nSign

Architecture: Exclusively reported on arm64-v8a architecture.

Artifact/Image: The crash occurs within a Split APK file, strongly suggesting a potential conflict with the loading/mapping process of the native library via Android App Bundles (AAB).

split_config.arm64_v8a.apk

Sentry Stack Trace Excerpt:

SIGBUS: BusError
split_config.arm64_v8a.apk 0x78232e79d0 null
...
split_config.arm64_v8a.apk 0x78232fea90 Java_com_adjust_sdk_sig_NativeLibHelper_nSign
...
Debug ID: b6cbc16b-f0f8-dbc4-b3f0-91dfb7dd9a1b

Context and Reproduction Attempts
SDK Version History: Crash started on v5.4.0 and continues on v5.4.1.

Environment: The crash is tied to devices using ARM64-v8a and the App Bundle distribution method.

Diagnosis: A SIGBUS in native code often indicates an issue with memory alignment or corrupted memory mapping when the library (.so) is loaded from the split_config.arm64_v8a.apk.

Mitigation Attempt: We have confirmed the ProGuard/R8 rules are correctly configured to keep the com.adjust.sdk.sig.** classes.

We suspect a low-level bug in the native signature library's implementation for ARM64-v8a in the v5.4.x branch, particularly how it interacts with the dynamic loading/mapping of split APKs.

We need urgent assistance in identifying if this is a known issue patched in a later 5.x version (e.g., 5.4.5) or if it requires a specific fix from the Adjust team.

Thank you for your time and assistance.

[dimim]

Hi @sebastianpeya.

Thank you for raising this topic & the mitigation attempts. We treat crashes as critical-priority tasks.

Overview & relevant pointers:

• Unless you've deviated from the defaults, the last SDK Signature library version you are using is 3.47.0. Signature is a dependency of the Adjust SDK
• Signature's releases are here and its documentation is here
• v3.47.0 has been running as Stable since June, 2025, with a Beta period between April-June, 2025
• We had nor have any reports of stability issues, in the Stable or Beta version [1]

We need urgent assistance in identifying if this is a known issue patched in a later 5.x version (e.g., 5.4.5) or if it requires a specific fix from the Adjust team.

Newer SDK versions target a newer version of Signature, but as [1] is the case, a blind update isn't going to help. The topic needs to be checked thoroughly.

Next steps

As what's written here is public, can I please ask you to reach out to Adjust's Support? Reason: Sensitive information is required and may be shared. To speed up the process, please link to this issue and provide (to the extent possible):

• App token
• Signature versions, if different than the default versions
• The affected APK files of the app
• List of devices affected, with the associated OS versions
• When the issue appears (does it e.g. appear upon the app launching?)
• Any full logs associated with the behaviour seen (e.g. execution logs, stack trace)
• I also understand there's no local reproducibility of the crash. Kindly confirm

Happy for thoughts.