From 93fe51840ebf2e2ea0c29d3c5aa196e328129469 Mon Sep 17 00:00:00 2001 From: Martijn Coenen Date: Wed, 22 Jan 2020 10:46:25 +0100 Subject: 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) --- libs/binder/BufferedTextOutput.cpp | 3 ++- libs/binder/Parcel.cpp | 10 ++++++++-- 2 files changed, 10 insertions(+), 3 deletions(-) diff --git a/libs/binder/BufferedTextOutput.cpp b/libs/binder/BufferedTextOutput.cpp index 857bbf9510..2978b539d7 100644 --- a/libs/binder/BufferedTextOutput.cpp +++ b/libs/binder/BufferedTextOutput.cpp @@ -49,9 +49,10 @@ struct BufferedTextOutput::BufferState : public RefBase } 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; diff --git a/libs/binder/Parcel.cpp b/libs/binder/Parcel.cpp index 5ad30271d7..11441eca64 100644 --- a/libs/binder/Parcel.cpp +++ b/libs/binder/Parcel.cpp @@ -520,8 +520,10 @@ status_t Parcel::appendFrom(const Parcel *parcel, size_t offset, size_t len) const sp 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 @@ restart_write: 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 @@ status_t Parcel::growData(size_t len) 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 -- cgit v1.2.3