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: I738b90855b6b9a8effbf55a468c751b6d0b8edd9
(cherry picked from commit d79ac373483c36f893981c7319d37a5ebbd63b98)
diff --git a/BufferedTextOutput.cpp b/BufferedTextOutput.cpp
index 3c7db8b..1b340a3 100644
--- a/BufferedTextOutput.cpp
+++ b/BufferedTextOutput.cpp
@@ -52,15 +52,15 @@
}
status_t append(const char* txt, size_t len) {
+ if (len > SIZE_MAX - bufferPos) return NO_MEMORY; // overflow
if ((len+bufferPos) > bufferSize) {
+ if ((len + bufferPos) > SIZE_MAX / 3) return NO_MEMORY; // overflow
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;
}
- if ((len+bufferPos) < bufferPos) return NO_MEMORY; // integer overflow
memcpy(buffer+bufferPos, txt, len);
bufferPos += len;
return NO_ERROR;
diff --git a/Parcel.cpp b/Parcel.cpp
index d6ea481..e769b1f 100644
--- a/Parcel.cpp
+++ b/Parcel.cpp
@@ -778,8 +778,10 @@
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;
@@ -1976,11 +1978,10 @@
// inadvertent conversion from a negative int.
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
- : continueWrite(newSize);
+ return continueWrite(newSize);
}
status_t Parcel::restartWrite(size_t desired)
