tree b860653c60495dfe08e79e3015e375bcf4f8cfaa
parent ad00dc0482b80a76e4de22193721f35d02a1cffe
author Tej Singh <singhtejinder@google.com> 1569032933 -0700
committer Bryan Ferris <bferris@google.com> 1576702682 -0800

Security Fix: Race Condition + NPE

ShellSubscriber is lazily initialized, and multiple threads can attempt
to write the same pointer since it is not initialized in threadsafe
code. Additionally, there is an NPE that crashes statsd when a null
ResultReceiver is passed in, which allows an attacker to repeatedly
crash statsd until the race condition occurs. More details, including a
proof of concept attack, are in the bug.

Bug: 141243101
Test: repro steps in bug no longer crash statsd
Test: with only the lock on iniitiallizing mShellSubscriber, statsd
still crashed but after ~7 minutes, no race condition occurred.

Change-Id: Ib56f888620497fb41d1627c07867693eb251738e