Fix infinite recursion in hashcode of Spannables

An app created a SpannableStringBuilder, one of which's spans was the
instance of the string builder itself (that is, the builder contained a span
that was the builder). This caused infinite recursion in the hashcode()
method because it computes a hash from its fields, including all of its spans.

The fix detects the case where a span equals the current instance and
noops the computation on that span. A similar adjustment was made to equals()
to avoid the same recursion problem.

Issue #11051658 StackOverflowError in android.text.SpannableStringBuilder.hashCode

Change-Id: I742687ab32d81ac51c4b9135f698cf5e96a1d295

2 files changed, 32 insertions, 16 deletions

diff --git a/core/java/android/text/SpannableStringBuilder.java b/core/java/android/text/SpannableStringBuilder.java
index 6efde05..34274a6 100644
--- a/core/java/android/text/SpannableStringBuilder.java
+++ b/core/java/android/text/SpannableStringBuilder.java
@@ -1293,23 +1293,29 @@ public class SpannableStringBuilder implements CharSequence, GetChars, Spannable
     public boolean equals(Object o) {
         if (o instanceof Spanned &&
                 toString().equals(o.toString())) {
+            Spanned other = (Spanned) o;
             // Check span data
-            Object[] otherSpans = ((Spanned) o).getSpans(0,
-                    ((Spanned) o).length(), Object.class);
+            Object[] otherSpans = other.getSpans(0, other.length(), Object.class);
             if (mSpanCount == otherSpans.length) {
                 for (int i = 0; i < mSpanCount; ++i) {
                     Object thisSpan = mSpans[i];
                     Object otherSpan = otherSpans[i];
-                    if (!thisSpan.equals(otherSpan) ||
-                            getSpanStart(thisSpan) != getSpanStart(otherSpan) ||
-                            getSpanEnd(thisSpan) != getSpanEnd(otherSpan) ||
-                            getSpanFlags(thisSpan) != getSpanFlags(otherSpan)) {
+                    if (thisSpan == this) {
+                        if (other != otherSpan ||
+                                getSpanStart(thisSpan) != other.getSpanStart(otherSpan) ||
+                                getSpanEnd(thisSpan) != other.getSpanEnd(otherSpan) ||
+                                getSpanFlags(thisSpan) != other.getSpanFlags(otherSpan)) {
+                            return false;
+                        }
+                    } else if (!thisSpan.equals(otherSpan) ||
+                            getSpanStart(thisSpan) != other.getSpanStart(otherSpan) ||
+                            getSpanEnd(thisSpan) != other.getSpanEnd(otherSpan) ||
+                            getSpanFlags(thisSpan) != other.getSpanFlags(otherSpan)) {
                         return false;
                     }
                 }
                 return true;
             }
-
         }
         return false;
     }
@@ -1321,7 +1327,9 @@ public class SpannableStringBuilder implements CharSequence, GetChars, Spannable
         hash = hash * 31 + mSpanCount;
         for (int i = 0; i < mSpanCount; ++i) {
             Object span = mSpans[i];
-            hash = hash * 31 + span.hashCode();
+            if (span != this) {
+                hash = hash * 31 + span.hashCode();
+            }
             hash = hash * 31 + getSpanStart(span);
             hash = hash * 31 + getSpanEnd(span);
             hash = hash * 31 + getSpanFlags(span);
diff --git a/core/java/android/text/SpannableStringInternal.java b/core/java/android/text/SpannableStringInternal.java
index 9b24a2e..456a3e5 100644
--- a/core/java/android/text/SpannableStringInternal.java
+++ b/core/java/android/text/SpannableStringInternal.java
@@ -363,23 +363,29 @@ import java.lang.reflect.Array;
     public boolean equals(Object o) {
         if (o instanceof Spanned &&
                 toString().equals(o.toString())) {
+            Spanned other = (Spanned) o;
             // Check span data
-            Object[] otherSpans = ((Spanned) o).getSpans(0,
-                    ((Spanned) o).length(), Object.class);
+            Object[] otherSpans = other.getSpans(0, other.length(), Object.class);
             if (mSpanCount == otherSpans.length) {
                 for (int i = 0; i < mSpanCount; ++i) {
                     Object thisSpan = mSpans[i];
                     Object otherSpan = otherSpans[i];
-                    if (!thisSpan.equals(otherSpan) ||
-                            getSpanStart(thisSpan) != getSpanStart(otherSpan) ||
-                            getSpanEnd(thisSpan) != getSpanEnd(otherSpan) ||
-                            getSpanFlags(thisSpan) != getSpanFlags(otherSpan)) {
+                    if (thisSpan == this) {
+                        if (other != otherSpan ||
+                                getSpanStart(thisSpan) != other.getSpanStart(otherSpan) ||
+                                getSpanEnd(thisSpan) != other.getSpanEnd(otherSpan) ||
+                                getSpanFlags(thisSpan) != other.getSpanFlags(otherSpan)) {
+                            return false;
+                        }
+                    } else if (!thisSpan.equals(otherSpan) ||
+                            getSpanStart(thisSpan) != other.getSpanStart(otherSpan) ||
+                            getSpanEnd(thisSpan) != other.getSpanEnd(otherSpan) ||
+                            getSpanFlags(thisSpan) != other.getSpanFlags(otherSpan)) {
                         return false;
                     }
                 }
                 return true;
             }
-
         }
         return false;
     }
@@ -391,7 +397,9 @@ import java.lang.reflect.Array;
         hash = hash * 31 + mSpanCount;
         for (int i = 0; i < mSpanCount; ++i) {
             Object span = mSpans[i];
-            hash = hash * 31 + span.hashCode();
+            if (span != this) {
+                hash = hash * 31 + span.hashCode();
+            }
             hash = hash * 31 + getSpanStart(span);
             hash = hash * 31 + getSpanEnd(span);
             hash = hash * 31 + getSpanFlags(span);