Add fuzzer for rewritten CursorWindow.
We recently rewrote CursorWindow, so let's get a fuzzer wired up
to see if it has any bugs.
This change creates a separate "libandroidfw_fuzz" library, since we
can't link to libbinder when building Windows host-side binaries;
the fuzzer doesn't need Window support.
And fix our first vulnerability where getFieldSlot() could be
tricked into reading out of bounds data.
The included corpus seed was generated using this example code:
CursorWindow* w = nullptr;
CursorWindow::create(android::String8("test"), 1 << 21, &w);
w->setNumColumns(3);
w->allocRow();
w->putLong(0,0,0xcafe);
w->putLong(0,1,0xcafe);
w->putLong(0,2,0xcafe);
// Row purposefully left empty
w->allocRow();
w->allocRow();
w->putNull(2,0);
w->putNull(2,1);
w->putNull(2,2);
w->allocRow();
w->putString(3,0,"cafe",5);
w->putString(3,1,"cafe",5);
w->putString(3,2,"cafe",5);
w->allocRow();
w->putDouble(4,0,3.14159f);
w->putDouble(4,1,3.14159f);
w->putDouble(4,2,3.14159f);
Parcel p;
w->writeToParcel(&p);
Bug: 169251528
Test: atest libandroidfw_tests:CursorWindowTest
Test: SANITIZE_HOST=address make ${FUZZER_NAME} && ${ANDROID_HOST_OUT}/fuzz/$(get_build_var HOST_ARCH)/${FUZZER_NAME}/${FUZZER_NAME}
Change-Id: I405d377900943de0ad732d3f1a1a0970e17d5140
diff --git a/libs/androidfw/CursorWindow.cpp b/libs/androidfw/CursorWindow.cpp
index 1e6de67..915c0d7 100644
--- a/libs/androidfw/CursorWindow.cpp
+++ b/libs/androidfw/CursorWindow.cpp
@@ -251,7 +251,8 @@
}
void CursorWindow::updateSlotsData() {
- mSlotsData = static_cast<uint8_t*>(mData) + mSize - kSlotSizeBytes;
+ mSlotsStart = static_cast<uint8_t*>(mData) + mSize - kSlotSizeBytes;
+ mSlotsEnd = static_cast<uint8_t*>(mData) + mSlotsOffset;
}
void* CursorWindow::offsetToPtr(uint32_t offset, uint32_t bufferSize = 0) {
@@ -300,6 +301,7 @@
}
memset(offsetToPtr(newOffset), 0, size);
mSlotsOffset = newOffset;
+ updateSlotsData();
mNumRows++;
return OK;
}
@@ -314,6 +316,7 @@
return NO_MEMORY;
}
mSlotsOffset = newOffset;
+ updateSlotsData();
mNumRows--;
return OK;
}
@@ -337,18 +340,18 @@
}
CursorWindow::FieldSlot* CursorWindow::getFieldSlot(uint32_t row, uint32_t column) {
- if (row >= mNumRows || column >= mNumColumns) {
- LOG(ERROR) << "Failed to read row " << row << ", column " << column
- << " from a window with " << mNumRows << " rows, " << mNumColumns << " columns";
- return nullptr;
- }
-
// This is carefully tuned to use as few cycles as
// possible, since this is an extremely hot code path;
// see CursorWindow_bench.cpp for more details
- void *result = static_cast<uint8_t*>(mSlotsData)
+ void *result = static_cast<uint8_t*>(mSlotsStart)
- (((row * mNumColumns) + column) << kSlotShift);
- return static_cast<FieldSlot*>(result);
+ if (result < mSlotsEnd || column >= mNumColumns) {
+ LOG(ERROR) << "Failed to read row " << row << ", column " << column
+ << " from a window with " << mNumRows << " rows, " << mNumColumns << " columns";
+ return nullptr;
+ } else {
+ return static_cast<FieldSlot*>(result);
+ }
}
status_t CursorWindow::putBlob(uint32_t row, uint32_t column, const void* value, size_t size) {
