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GrapheneOS / os-issue-tracker

Issue tracker for GrapheneOS Android Open Source Project hardening work. Standalone projects like Auditor, AttestationServer and hardened_malloc have their own dedicated trackers.
https://grapheneos.org/
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App (brawl star) crash, probably libc problem #532

Closed Adriankhl closed 3 years ago

Adriankhl commented 3 years ago

GrapheneOS version: RQ2A.210305.006.2021.03.19.14 Phone: Pixel 4a (5G)

This has been a thing since I installed GrapheneOS on my phone few weeks ago. The brawl star game app (which I installed via Aurora store) seems to be crashing a lot. The app simply close and exit to main screen without any error message. This can happen at anytime so it is hard to reproduce the issue reliably.

From the exported bug report, I can identify the line

04-03 16:30:25.447 10200 24412 24489 F libc    : Fatal signal 11 (SIGSEGV), code 2 (SEGV_ACCERR), fault addr 0xdb93e8fc2f95 in tid 24489 (cell.brawlstars), pid 24412 (cell.brawlstars)

so I guess it is something related to the libc of GrapheneOS. However, since other apps seem to be functioning normally, it is possible that the problem is at the app side rather than at the OS side.

This is the bug report: bugreport-aosp_bramble-RQ2A.210305.006-2021-04-03-16-43-49.txt

And this is the tombstone: tombstone_10.txt

I know very little of debugging Android stuff, so I am happy to hear any advise to further trace the problem.

thestinger commented 3 years ago

Looks like a memory corruption in the app that's being detected. You really need to report this to the app developer.

See https://grapheneos.org/usage#bugs-uncovered-by-security-features.

thestinger commented 3 years ago

I think this is either a use-after-free or buffer overflow detected via hardened_malloc. The best thing to do is report the bug to the app developer and encourage them to run their app with Valgrind or ideally build it with ASan (Address Sanitizer) and test that way. They may also be able to use Android's debug malloc features but those aren't very good.

thestinger commented 3 years ago

Don't think we can do much about this. Appears to be an app issue. They need to fix the memory corruption bugs.