From ed7a50cc7d490ae7aece2d16422c5f7941876468 Mon Sep 17 00:00:00 2001 From: Christopher Tate Date: Mon, 8 Jun 2015 14:45:14 -0700 Subject: [PATCH] Prevent integer overflow when calculating buffer resizes Make sure that we don't go haywire if an exponential buffer growth operation winds up wrapping integer range. Along the way, fix a bookkeeping bug in BufferedTextOutput that would cause it to keep spuriously realloc()ing on every append(). Bug 20674694 Change-Id: Ia845b7de36b90672a151a918ffc26c7da68e20a2 --- libs/binder/BufferedTextOutput.cpp | 5 ++++- libs/binder/Parcel.cpp | 4 +++- 2 files changed, 7 insertions(+), 2 deletions(-) diff --git a/libs/binder/BufferedTextOutput.cpp b/libs/binder/BufferedTextOutput.cpp index 2d493c151..1339a67e6 100644 --- a/libs/binder/BufferedTextOutput.cpp +++ b/libs/binder/BufferedTextOutput.cpp @@ -49,9 +49,12 @@ struct BufferedTextOutput::BufferState : public RefBase status_t append(const char* txt, size_t len) { if ((len+bufferPos) > bufferSize) { - void* b = realloc(buffer, ((len+bufferPos)*3)/2); + size_t newSize = ((len+bufferPos)*3)/2; + if (newSize < (len+bufferPos)) return NO_MEMORY; // overflow + void* b = realloc(buffer, newSize); if (!b) return NO_MEMORY; buffer = (char*)b; + bufferSize = newSize; } memcpy(buffer+bufferPos, txt, len); bufferPos += len; diff --git a/libs/binder/Parcel.cpp b/libs/binder/Parcel.cpp index 2ebf617cf..31667d932 100644 --- a/libs/binder/Parcel.cpp +++ b/libs/binder/Parcel.cpp @@ -484,7 +484,8 @@ status_t Parcel::appendFrom(const Parcel *parcel, size_t offset, size_t len) if (numObjects > 0) { // grow objects if (mObjectsCapacity < mObjectsSize + numObjects) { - int newSize = ((mObjectsSize + numObjects)*3)/2; + size_t newSize = ((mObjectsSize + numObjects)*3)/2; + if (newSize < mObjectsSize) return NO_MEMORY; // overflow binder_size_t *objects = (binder_size_t*)realloc(mObjects, newSize*sizeof(binder_size_t)); if (objects == (binder_size_t*)0) { @@ -1038,6 +1039,7 @@ restart_write: } if (!enoughObjects) { size_t newSize = ((mObjectsSize+2)*3)/2; + if (newSize < mObjectsSize) return NO_MEMORY; // overflow binder_size_t* objects = (binder_size_t*)realloc(mObjects, newSize*sizeof(binder_size_t)); if (objects == NULL) return NO_MEMORY; mObjects = objects;