Fix addition/overflow checks.
For unsigned arithmetic, use:
(a + b < a) to detect whether a+b wraps
(a > c / b) to detect whether a*b > c
Bug: 120078455
Test: builds and boots
Change-Id: Ic4f4d44f7c0656caa115f90f4cfa130192914949
(cherry picked from commit da2f2fd0f4c4eeb498b4b0541719f4f34faf13e2)
diff --git a/libs/binder/Parcel.cpp b/libs/binder/Parcel.cpp
index 5ad3027..11441ec 100644
--- a/libs/binder/Parcel.cpp
+++ b/libs/binder/Parcel.cpp
@@ -520,8 +520,10 @@
const sp<ProcessState> proc(ProcessState::self());
// grow objects
if (mObjectsCapacity < mObjectsSize + numObjects) {
+ if ((size_t) numObjects > SIZE_MAX - mObjectsSize) return NO_MEMORY; // overflow
+ if (mObjectsSize + numObjects > SIZE_MAX / 3) return NO_MEMORY; // overflow
size_t newSize = ((mObjectsSize + numObjects)*3)/2;
- if (newSize*sizeof(binder_size_t) < mObjectsSize) return NO_MEMORY; // overflow
+ if (newSize > SIZE_MAX / sizeof(binder_size_t)) return NO_MEMORY; // overflow
binder_size_t *objects =
(binder_size_t*)realloc(mObjects, newSize*sizeof(binder_size_t));
if (objects == (binder_size_t*)nullptr) {
@@ -1399,8 +1401,10 @@
if (err != NO_ERROR) return err;
}
if (!enoughObjects) {
+ if (mObjectsSize > SIZE_MAX - 2) return NO_MEMORY; // overflow
+ if ((mObjectsSize + 2) > SIZE_MAX / 3) return NO_MEMORY; // overflow
size_t newSize = ((mObjectsSize+2)*3)/2;
- if (newSize*sizeof(binder_size_t) < mObjectsSize) return NO_MEMORY; // overflow
+ if (newSize > SIZE_MAX / sizeof(binder_size_t)) return NO_MEMORY; // overflow
binder_size_t* objects = (binder_size_t*)realloc(mObjects, newSize*sizeof(binder_size_t));
if (objects == nullptr) return NO_MEMORY;
mObjects = objects;
@@ -2685,6 +2689,8 @@
return BAD_VALUE;
}
+ if (len > SIZE_MAX - mDataSize) return NO_MEMORY; // overflow
+ if (mDataSize + len > SIZE_MAX / 3) return NO_MEMORY; // overflow
size_t newSize = ((mDataSize+len)*3)/2;
return (newSize <= mDataSize)
? (status_t) NO_MEMORY