From 0ebe70cb0fa685693d7834b4b4ee94515149c8fb Mon Sep 17 00:00:00 2001
From: Wilson Wu <wilsonwu@google.com>
Date: Fri, 17 Jul 2020 23:50:45 +0800
Subject: [PATCH] Prevent exception when surrounding text retrieval

We use same reference from TextView to set the initial
surrounding text. The actual surrounding text may be
modified before retrieval since the mSurroundingText
is mutable. Use a copy of subText should avoid this
concurrent issue.

Bug: 160390184
Test: atest FrameworksCoreTests:EditorInfoTest
Change-Id: I6082a4cae2fcdc4c529dc14e2e5e7a45ab1aae4d
---
 .../android/view/inputmethod/EditorInfo.java  | 10 ++++++----
 .../view/inputmethod/EditorInfoTest.java      | 19 +++++++++++++++++++
 2 files changed, 25 insertions(+), 4 deletions(-)

diff --git a/core/java/android/view/inputmethod/EditorInfo.java b/core/java/android/view/inputmethod/EditorInfo.java
index 07fef76961f95..c5f2299e4f83b 100644
--- a/core/java/android/view/inputmethod/EditorInfo.java
+++ b/core/java/android/view/inputmethod/EditorInfo.java
@@ -27,6 +27,7 @@ import android.os.LocaleList;
 import android.os.Parcel;
 import android.os.Parcelable;
 import android.os.UserHandle;
+import android.text.Editable;
 import android.text.InputType;
 import android.text.TextUtils;
 import android.util.Printer;
@@ -567,7 +568,8 @@ public class EditorInfo implements InputType, Parcelable {
      *                      editor wants to trim out the first 10 chars, subTextStart should be 10.
      */
     public void setInitialSurroundingSubText(@NonNull CharSequence subText, int subTextStart) {
-        Objects.requireNonNull(subText);
+        CharSequence newSubText = Editable.Factory.getInstance().newEditable(subText);
+        Objects.requireNonNull(newSubText);
 
         // Swap selection start and end if necessary.
         final int subTextSelStart = initialSelStart > initialSelEnd
@@ -575,7 +577,7 @@ public class EditorInfo implements InputType, Parcelable {
         final int subTextSelEnd = initialSelStart > initialSelEnd
                 ? initialSelStart - subTextStart : initialSelEnd - subTextStart;
 
-        final int subTextLength = subText.length();
+        final int subTextLength = newSubText.length();
         // Unknown or invalid selection.
         if (subTextStart < 0 || subTextSelStart < 0 || subTextSelEnd > subTextLength) {
             mInitialSurroundingText = new InitialSurroundingText();
@@ -589,12 +591,12 @@ public class EditorInfo implements InputType, Parcelable {
         }
 
         if (subTextLength <= MEMORY_EFFICIENT_TEXT_LENGTH) {
-            mInitialSurroundingText = new InitialSurroundingText(subText, subTextSelStart,
+            mInitialSurroundingText = new InitialSurroundingText(newSubText, subTextSelStart,
                     subTextSelEnd);
             return;
         }
 
-        trimLongSurroundingText(subText, subTextSelStart, subTextSelEnd);
+        trimLongSurroundingText(newSubText, subTextSelStart, subTextSelEnd);
     }
 
     /**
diff --git a/core/tests/coretests/src/android/view/inputmethod/EditorInfoTest.java b/core/tests/coretests/src/android/view/inputmethod/EditorInfoTest.java
index 02ffc00dcba53..93de03adfa845 100644
--- a/core/tests/coretests/src/android/view/inputmethod/EditorInfoTest.java
+++ b/core/tests/coretests/src/android/view/inputmethod/EditorInfoTest.java
@@ -264,6 +264,25 @@ public class EditorInfoTest {
                         InputConnection.GET_TEXT_WITH_STYLES)));
     }
 
+    @Test
+    public void surroundingTextRetrieval_writeToParcel_noException() {
+        StringBuilder sb = new StringBuilder("abcdefg");
+        Parcel parcel = Parcel.obtain();
+        EditorInfo editorInfo = new EditorInfo();
+        editorInfo.initialSelStart = 2;
+        editorInfo.initialSelEnd = 5;
+        editorInfo.inputType = EditorInfo.TYPE_CLASS_TEXT;
+
+        editorInfo.setInitialSurroundingText(sb);
+        sb.setLength(0);
+        editorInfo.writeToParcel(parcel, 0);
+
+        try {
+            editorInfo.getInitialTextBeforeCursor(60, 1);
+            fail("Test shouldn't have exception");
+        } catch (AssertionError e) { }
+    }
+
     private static void assertExpectedTextLength(EditorInfo editorInfo,
             @Nullable Integer expectBeforeCursorLength, @Nullable Integer expectSelectionLength,
             @Nullable Integer expectAfterCursorLength) {