diff --git a/libutils/FileMap.cpp b/libutils/FileMap.cpp
index 1d899ab..0abb861 100644
--- a/libutils/FileMap.cpp
+++ b/libutils/FileMap.cpp
@@ -189,7 +189,11 @@
 
     int adjust = offset % mPageSize;
     off64_t adjOffset = offset - adjust;
-    size_t adjLength = length + adjust;
+    size_t adjLength;
+    if (__builtin_add_overflow(length, adjust, &adjLength)) {
+        ALOGE("adjusted length overflow: length %zu adjust %d", length, adjust);
+        return false;
+    }
 
     int flags = MAP_SHARED;
     int prot = PROT_READ;
diff --git a/libutils/FileMap_test.cpp b/libutils/FileMap_test.cpp
index 9f7ce85..fd1c9b0 100644
--- a/libutils/FileMap_test.cpp
+++ b/libutils/FileMap_test.cpp
@@ -52,3 +52,16 @@
     ASSERT_EQ(0u, m.getDataLength());
     ASSERT_EQ(offset, m.getDataOffset());
 }
+
+TEST(FileMap, offset_overflow) {
+    // Make sure that an end that overflows SIZE_MAX will not abort.
+    // See http://b/156997193.
+    TemporaryFile tf;
+    ASSERT_TRUE(tf.fd != -1);
+
+    off64_t offset = 200;
+    size_t length = SIZE_MAX;
+
+    android::FileMap m;
+    ASSERT_FALSE(m.create("test", tf.fd, offset, length, true));
+}