Commit 17de8898 authored Jan 13, 2021 by Mitch Phillips

[MTE] Enable ASYNC MTE in the Zygote.

This allows applications to turn on MTE. The current design of MTE
inside of Scudo doesn't allow us to late-enable MTE (but we can
late-disable it). Thus, we have to enable tagging in the Zygote in order
to allow apps and the system_server to control their own MTE behaviour.

We intentionally use ASYNC mode so that we don't waste memory collecting
stack traces from the zygote pre-fork. Given that the zygote is mostly
Java code, the process itself should be pretty low risk for memory
corruption.

Bug: 135772972
Bug: 172365548
Test: On FVP: atest -s localhost:5555 \
com.android.cts.tagging.TaggingSdk30Test#testMemoryTagChecksCompatFeatureEnabled \
com.android.cts.tagging.TaggingSdk30Test#testMemoryTagChecksCompatFeatureDisabled

Change-Id: I9da2c33cb6022033264f443308d5508b3ff8da9e

parent 5be93c28

cmds/app_process/Android.bp

+9 −0

Original line number	Diff line number	Diff line
		@@ -62,4 +62,13 @@ cc_binary {
		// Create a symlink from app_process to app_process32 or 64
		// depending on the target configuration.
		symlink_preferred_arch: true,

		// Enable ASYNC MTE in the zygote, in order to allow apps and the system
		// server to use MTE. We use ASYNC because we don't expect the pre-fork
		// zygote to have substantial memory corruption bugs (as it's primarily Java
		// code), and we don't want to waste memory recording malloc/free stack
		// traces (which happens in SYNC mode).
		sanitize: {
		memtag_heap: true,
		},
		}