Do not modify vector after getting references

We used to obtain a reference to a specific element inside a vector. We
would then modify the vector, invalidating the reference. But we then
used the reference, and passed it to 'assignPointerIds'.

Refactor the code to modify the collection first, and then to proceed
with modifying / reading the elements.

Bug: 179839665
Test: atest inputflinger_tests (on a hwasan build)
Merged-In: I9204b954884e9c83a50babdad5e08a0f6d18ad78
Change-Id: I9204b954884e9c83a50babdad5e08a0f6d18ad78
(cherry picked from commit 8cf78f9553981600f57e9c829886848172114484)

2 files changed, 39 insertions, 38 deletions

diff --git a/services/inputflinger/reader/mapper/TouchInputMapper.cpp b/services/inputflinger/reader/mapper/TouchInputMapper.cpp
index 99a572a5fd..decbea4c3e 100644
--- a/services/inputflinger/reader/mapper/TouchInputMapper.cpp
+++ b/services/inputflinger/reader/mapper/TouchInputMapper.cpp
@@ -1413,27 +1413,28 @@ void TouchInputMapper::process(const RawEvent* rawEvent) {
 }
 
 void TouchInputMapper::sync(nsecs_t when) {
-    const RawState* last =
-            mRawStatesPending.empty() ? &mCurrentRawState : &mRawStatesPending.back();
-
     // Push a new state.
     mRawStatesPending.emplace_back();
 
-    RawState* next = &mRawStatesPending.back();
-    next->clear();
-    next->when = when;
+    RawState& next = mRawStatesPending.back();
+    next.clear();
+    next.when = when;
 
     // Sync button state.
-    next->buttonState =
+    next.buttonState =
             mTouchButtonAccumulator.getButtonState() | mCursorButtonAccumulator.getButtonState();
 
     // Sync scroll
-    next->rawVScroll = mCursorScrollAccumulator.getRelativeVWheel();
-    next->rawHScroll = mCursorScrollAccumulator.getRelativeHWheel();
+    next.rawVScroll = mCursorScrollAccumulator.getRelativeVWheel();
+    next.rawHScroll = mCursorScrollAccumulator.getRelativeHWheel();
     mCursorScrollAccumulator.finishSync();
 
     // Sync touch
-    syncTouch(when, next);
+    syncTouch(when, &next);
+
+    // The last RawState is the actually second to last, since we just added a new state
+    const RawState& last =
+            mRawStatesPending.size() == 1 ? mCurrentRawState : mRawStatesPending.rbegin()[1];
 
     // Assign pointer ids.
     if (!mHavePointerIds) {
@@ -1443,9 +1444,9 @@ void TouchInputMapper::sync(nsecs_t when) {
 #if DEBUG_RAW_EVENTS
     ALOGD("syncTouch: pointerCount %d -> %d, touching ids 0x%08x -> 0x%08x, "
           "hovering ids 0x%08x -> 0x%08x",
-          last->rawPointerData.pointerCount, next->rawPointerData.pointerCount,
-          last->rawPointerData.touchingIdBits.value, next->rawPointerData.touchingIdBits.value,
-          last->rawPointerData.hoveringIdBits.value, next->rawPointerData.hoveringIdBits.value);
+          last.rawPointerData.pointerCount, next.rawPointerData.pointerCount,
+          last.rawPointerData.touchingIdBits.value, next.rawPointerData.touchingIdBits.value,
+          last.rawPointerData.hoveringIdBits.value, next.rawPointerData.hoveringIdBits.value);
 #endif
 
     processRawTouches(false /*timeout*/);
@@ -3679,11 +3680,11 @@ const TouchInputMapper::VirtualKey* TouchInputMapper::findVirtualKeyHit(int32_t
     return nullptr;
 }
 
-void TouchInputMapper::assignPointerIds(const RawState* last, RawState* current) {
-    uint32_t currentPointerCount = current->rawPointerData.pointerCount;
-    uint32_t lastPointerCount = last->rawPointerData.pointerCount;
+void TouchInputMapper::assignPointerIds(const RawState& last, RawState& current) {
+    uint32_t currentPointerCount = current.rawPointerData.pointerCount;
+    uint32_t lastPointerCount = last.rawPointerData.pointerCount;
 
-    current->rawPointerData.clearIdBits();
+    current.rawPointerData.clearIdBits();
 
     if (currentPointerCount == 0) {
         // No pointers to assign.
@@ -3694,20 +3695,20 @@ void TouchInputMapper::assignPointerIds(const RawState* last, RawState* current)
         // All pointers are new.
         for (uint32_t i = 0; i < currentPointerCount; i++) {
             uint32_t id = i;
-            current->rawPointerData.pointers[i].id = id;
-            current->rawPointerData.idToIndex[id] = i;
-            current->rawPointerData.markIdBit(id, current->rawPointerData.isHovering(i));
+            current.rawPointerData.pointers[i].id = id;
+            current.rawPointerData.idToIndex[id] = i;
+            current.rawPointerData.markIdBit(id, current.rawPointerData.isHovering(i));
         }
         return;
     }
 
     if (currentPointerCount == 1 && lastPointerCount == 1 &&
-        current->rawPointerData.pointers[0].toolType == last->rawPointerData.pointers[0].toolType) {
+        current.rawPointerData.pointers[0].toolType == last.rawPointerData.pointers[0].toolType) {
         // Only one pointer and no change in count so it must have the same id as before.
-        uint32_t id = last->rawPointerData.pointers[0].id;
-        current->rawPointerData.pointers[0].id = id;
-        current->rawPointerData.idToIndex[id] = 0;
-        current->rawPointerData.markIdBit(id, current->rawPointerData.isHovering(0));
+        uint32_t id = last.rawPointerData.pointers[0].id;
+        current.rawPointerData.pointers[0].id = id;
+        current.rawPointerData.idToIndex[id] = 0;
+        current.rawPointerData.markIdBit(id, current.rawPointerData.isHovering(0));
         return;
     }
 
@@ -3725,9 +3726,9 @@ void TouchInputMapper::assignPointerIds(const RawState* last, RawState* current)
         for (uint32_t lastPointerIndex = 0; lastPointerIndex < lastPointerCount;
              lastPointerIndex++) {
             const RawPointerData::Pointer& currentPointer =
-                    current->rawPointerData.pointers[currentPointerIndex];
+                    current.rawPointerData.pointers[currentPointerIndex];
             const RawPointerData::Pointer& lastPointer =
-                    last->rawPointerData.pointers[lastPointerIndex];
+                    last.rawPointerData.pointers[lastPointerIndex];
             if (currentPointer.toolType == lastPointer.toolType) {
                 int64_t deltaX = currentPointer.x - lastPointer.x;
                 int64_t deltaY = currentPointer.y - lastPointer.y;
@@ -3831,12 +3832,12 @@ void TouchInputMapper::assignPointerIds(const RawState* last, RawState* current)
             matchedCurrentBits.markBit(currentPointerIndex);
             matchedLastBits.markBit(lastPointerIndex);
 
-            uint32_t id = last->rawPointerData.pointers[lastPointerIndex].id;
-            current->rawPointerData.pointers[currentPointerIndex].id = id;
-            current->rawPointerData.idToIndex[id] = currentPointerIndex;
-            current->rawPointerData.markIdBit(id,
-                                              current->rawPointerData.isHovering(
-                                                      currentPointerIndex));
+            uint32_t id = last.rawPointerData.pointers[lastPointerIndex].id;
+            current.rawPointerData.pointers[currentPointerIndex].id = id;
+            current.rawPointerData.idToIndex[id] = currentPointerIndex;
+            current.rawPointerData.markIdBit(id,
+                                             current.rawPointerData.isHovering(
+                                                     currentPointerIndex));
             usedIdBits.markBit(id);
 
 #if DEBUG_POINTER_ASSIGNMENT
@@ -3853,10 +3854,10 @@ void TouchInputMapper::assignPointerIds(const RawState* last, RawState* current)
         uint32_t currentPointerIndex = matchedCurrentBits.markFirstUnmarkedBit();
         uint32_t id = usedIdBits.markFirstUnmarkedBit();
 
-        current->rawPointerData.pointers[currentPointerIndex].id = id;
-        current->rawPointerData.idToIndex[id] = currentPointerIndex;
-        current->rawPointerData.markIdBit(id,
-                                          current->rawPointerData.isHovering(currentPointerIndex));
+        current.rawPointerData.pointers[currentPointerIndex].id = id;
+        current.rawPointerData.idToIndex[id] = currentPointerIndex;
+        current.rawPointerData.markIdBit(id,
+                                         current.rawPointerData.isHovering(currentPointerIndex));
 
 #if DEBUG_POINTER_ASSIGNMENT
         ALOGD("assignPointerIds - assigned: cur=%" PRIu32 ", id=%" PRIu32, currentPointerIndex, id);
diff --git a/services/inputflinger/reader/mapper/TouchInputMapper.h b/services/inputflinger/reader/mapper/TouchInputMapper.h
index 58bfc5c596..1c2cc18f91 100644
--- a/services/inputflinger/reader/mapper/TouchInputMapper.h
+++ b/services/inputflinger/reader/mapper/TouchInputMapper.h
@@ -758,7 +758,7 @@ private:
     bool isPointInsideSurface(int32_t x, int32_t y);
     const VirtualKey* findVirtualKeyHit(int32_t x, int32_t y);
 
-    static void assignPointerIds(const RawState* last, RawState* current);
+    static void assignPointerIds(const RawState& last, RawState& current);
 
     const char* modeToString(DeviceMode deviceMode);
     void rotateAndScale(float& x, float& y);