AAPT2: Fix parsing ResTable_type
ResTable_type's size changes due to it containing
ResTable_config. Make sure we check for the minimum size
required to read it.
Bug: 35861796
Test: Manual (don't have an integration test harness setup yet)
Change-Id: Ifb0cd1d732625f59835c8ed0449adb78129636de
diff --git a/libs/androidfw/LoadedArsc.cpp b/libs/androidfw/LoadedArsc.cpp
index db72f48..621d8c0 100644
--- a/libs/androidfw/LoadedArsc.cpp
+++ b/libs/androidfw/LoadedArsc.cpp
@@ -212,7 +212,7 @@
static bool VerifyType(const Chunk& chunk) {
ATRACE_CALL();
- const ResTable_type* header = chunk.header<ResTable_type>();
+ const ResTable_type* header = chunk.header<ResTable_type, kResTableTypeMinSize>();
const size_t entry_count = dtohl(header->entryCount);
if (entry_count > std::numeric_limits<uint16_t>::max()) {
@@ -533,7 +533,7 @@
} break;
case RES_TABLE_TYPE_TYPE: {
- const ResTable_type* type = child_chunk.header<ResTable_type>();
+ const ResTable_type* type = child_chunk.header<ResTable_type, kResTableTypeMinSize>();
if (type == nullptr) {
LOG(ERROR) << "Chunk RES_TABLE_TYPE_TYPE is too small.";
return {};
diff --git a/libs/androidfw/include/androidfw/Chunk.h b/libs/androidfw/include/androidfw/Chunk.h
index e87b940..89b588e 100644
--- a/libs/androidfw/include/androidfw/Chunk.h
+++ b/libs/androidfw/include/androidfw/Chunk.h
@@ -48,9 +48,9 @@
// Returns the size of the header. Caller need not worry about endianness.
inline size_t header_size() const { return dtohs(device_chunk_->headerSize); }
- template <typename T>
+ template <typename T, size_t MinSize = sizeof(T)>
inline const T* header() const {
- if (header_size() >= sizeof(T)) {
+ if (header_size() >= MinSize) {
return reinterpret_cast<const T*>(device_chunk_);
}
return nullptr;
diff --git a/libs/androidfw/include/androidfw/ResourceTypes.h b/libs/androidfw/include/androidfw/ResourceTypes.h
index d982a35..306ff9a 100644
--- a/libs/androidfw/include/androidfw/ResourceTypes.h
+++ b/libs/androidfw/include/androidfw/ResourceTypes.h
@@ -1391,11 +1391,20 @@
// Offset from header where ResTable_entry data starts.
uint32_t entriesStart;
-
- // Configuration this collection of entries is designed for.
+
+ // Configuration this collection of entries is designed for. This must always be last.
ResTable_config config;
};
+// The minimum size required to read any version of ResTable_type.
+constexpr size_t kResTableTypeMinSize =
+ sizeof(ResTable_type) - sizeof(ResTable_config) + sizeof(ResTable_config::size);
+
+// Assert that the ResTable_config is always the last field. This poses a problem for extending
+// ResTable_type in the future, as ResTable_config is variable (over different releases).
+static_assert(sizeof(ResTable_type) == offsetof(ResTable_type, config) + sizeof(ResTable_config),
+ "ResTable_config must be last field in ResTable_type");
+
/**
* An entry in a ResTable_type with the flag `FLAG_SPARSE` set.
*/
diff --git a/tools/aapt2/unflatten/BinaryResourceParser.cpp b/tools/aapt2/unflatten/BinaryResourceParser.cpp
index 9158bdd..66bcfa0 100644
--- a/tools/aapt2/unflatten/BinaryResourceParser.cpp
+++ b/tools/aapt2/unflatten/BinaryResourceParser.cpp
@@ -313,7 +313,9 @@
return false;
}
- const ResTable_type* type = ConvertTo<ResTable_type>(chunk);
+ // Specify a manual size, because ResTable_type contains ResTable_config, which changes
+ // a lot and has its own code to handle variable size.
+ const ResTable_type* type = ConvertTo<ResTable_type, kResTableTypeMinSize>(chunk);
if (!type) {
context_->GetDiagnostics()->Error(DiagMessage(source_)
<< "corrupt ResTable_type chunk");
diff --git a/tools/aapt2/unflatten/ResChunkPullParser.h b/tools/aapt2/unflatten/ResChunkPullParser.h
index 437fc5c..5827753 100644
--- a/tools/aapt2/unflatten/ResChunkPullParser.h
+++ b/tools/aapt2/unflatten/ResChunkPullParser.h
@@ -78,9 +78,9 @@
std::string error_;
};
-template <typename T>
+template <typename T, size_t MinSize = sizeof(T)>
inline static const T* ConvertTo(const android::ResChunk_header* chunk) {
- if (util::DeviceToHost16(chunk->headerSize) < sizeof(T)) {
+ if (util::DeviceToHost16(chunk->headerSize) < MinSize) {
return nullptr;
}
return reinterpret_cast<const T*>(chunk);