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
diff --git a/BufferedTextOutput.cpp b/BufferedTextOutput.cpp
index 2d493c1..1339a67 100644
--- a/BufferedTextOutput.cpp
+++ b/BufferedTextOutput.cpp
@@ -49,9 +49,12 @@
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;
