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Fix deadlock in StagingManager.getSessions() method

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When we stage a session we acquire the PackageInstallerSession#mLock
first and then StagingManager#mStagedSessions lock. But in getSessions()
method, we acquire the locks in reverse order which can lead to
deadlock: we first acquire StagingManager#mStagedSessions in
getSessions() and then while checking if session is destroyed, we
acquire PackageInstallerSession#mLock in isDestroyed() method.

By moving the staged session retrieval logic to PackageInstallerService,
we avoid acquiring the StagingManager#mStagedSession lock. This avoids
deadlock.

Bug: 160113544
Test: atest StagedInstallTest
Change-Id: I7a1abf44db27d4673d43e9b0886610a5bd8b41f6
Merged-In: I7a1abf44db27d4673d43e9b0886610a5bd8b41f6
(cherry picked from commit c45b6a146c)
This commit is contained in:
Mohammad Samiul Islam
2020-06-29 12:31:51 +01:00
parent 5a293b8eb2
commit 3aa1f5aa16
2 changed files with 10 additions and 16 deletions
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11
services/core/java/com/android/server/pm/PackageInstallerService.java
View File

@@ -865,7 +865,16 @@ public class PackageInstallerService extends IPackageInstaller.Stub implements
@Override
public ParceledListSlice<SessionInfo> getStagedSessions() {
return mStagingManager.getSessions(Binder.getCallingUid());
final List<SessionInfo> result = new ArrayList<>();
synchronized (mSessions) {
for (int i = 0; i < mSessions.size(); i++) {
final PackageInstallerSession session = mSessions.valueAt(i);
if (session.isStaged() && !session.isDestroyed()) {
result.add(session.generateInfoForCaller(false, Binder.getCallingUid()));
}
}
}
return new ParceledListSlice<>(result);
}
@Override

15
services/core/java/com/android/server/pm/StagingManager.java
View File

@@ -38,7 +38,6 @@ import android.content.pm.PackageManagerInternal;
import android.content.pm.PackageParser.PackageParserException;
import android.content.pm.PackageParser.SigningDetails;
import android.content.pm.PackageParser.SigningDetails.SignatureSchemeVersion;
import android.content.pm.ParceledListSlice;
import android.content.pm.parsing.PackageInfoWithoutStateUtils;
import android.content.rollback.IRollbackManager;
import android.content.rollback.RollbackInfo;
@@ -180,20 +179,6 @@ public class StagingManager {
}
}
ParceledListSlice<PackageInstaller.SessionInfo> getSessions(int callingUid) {
final List<PackageInstaller.SessionInfo> result = new ArrayList<>();
synchronized (mStagedSessions) {
for (int i = 0; i < mStagedSessions.size(); i++) {
final PackageInstallerSession stagedSession = mStagedSessions.valueAt(i);
if (stagedSession.isDestroyed()) {
continue;
}
result.add(stagedSession.generateInfoForCaller(false /*icon*/, callingUid));
}
}
return new ParceledListSlice<>(result);
}
/**
* Validates the signature used to sign the container of the new apex package
*