Prevent undefined behavior in RosAlloc.
In cases where remain == 0, the 32-bit value would be left shifted
32-bits, which is undefined behavior.
Change-Id: I6277279341b168536f928ce87375c395a1aa865c
diff --git a/runtime/gc/allocator/rosalloc.cc b/runtime/gc/allocator/rosalloc.cc
index 85234dc..49c7fda 100644
--- a/runtime/gc/allocator/rosalloc.cc
+++ b/runtime/gc/allocator/rosalloc.cc
@@ -1042,10 +1042,11 @@
inline uint32_t RosAlloc::Run::GetBitmapLastVectorMask(size_t num_slots, size_t num_vec) {
const size_t kBitsPerVec = 32;
- DCHECK_GE(num_slots * kBitsPerVec, num_vec);
+ DCHECK_GE(num_vec * kBitsPerVec, num_slots);
+ DCHECK_NE(num_vec, 0U);
size_t remain = num_vec * kBitsPerVec - num_slots;
- DCHECK_NE(remain, kBitsPerVec);
- return ((1U << remain) - 1) << (kBitsPerVec - remain);
+ DCHECK_LT(remain, kBitsPerVec);
+ return ((1U << remain) - 1) << ((kBitsPerVec - remain) & 0x1F);
}
inline bool RosAlloc::Run::IsAllFree() {
