Update maxNumber to be smaller.

There shouldn't be more than 4096 fds (probably signficantly smaller) and
there shouldn't be more than 4096 ints.

Bug: 18076253

Change-Id: I3a3e50ee3078a4710e9737114e65afc923ed0573

Author: Michael Lentine

libs/ui/GraphicBuffer.cpp

@@ -251,7 +251,11 @@ status_t GraphicBuffer::unflatten(
     const size_t numFds  = buf[6];
     const size_t numInts = buf[7];
 
-    const size_t maxNumber = UINT_MAX / sizeof(int);
+    // Limit the maxNumber to be relatively small. The number of fds or ints
+    // should not come close to this number, and the number itself was simply
+    // chosen to be high enough to not cause issues and low enough to prevent
+    // overflow problems.
+    const size_t maxNumber = 4096;
     if (numFds >= maxNumber || numInts >= (maxNumber - 8)) {
         width = height = stride = format = usage = 0;
         handle = NULL;