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Commit 984e8973 authored by Jason O'Brien's avatar Jason O'Brien
Browse files

Fix segfault with sparse encoding 

The native code that underlies `Resources#getIdentifier()` did not take
sparse encoding into account when calculating offsets, resulting in
either garbage or SEGV_MAPERR whenever a resource is first encountered
in a sparsely encoded configuration.

Bug: 197976367
Test: atest libandroidfw_tests --host
Change-Id: Ib7550fe2e05005550f59129a06be5712b74bc9c8
parent 2272f0a1

libs/androidfw/LoadedArsc.cpp

+11 −2
Original line number Diff line number Diff line
@@ -384,7 +384,16 @@ base::expected<uint32_t, NullOrIOError> LoadedPackage::FindEntryByName( 
        return base::unexpected(IOError::PAGES_MISSING);

      }



      auto offset = dtohl(entry_offset_ptr.value());

      uint32_t offset;

      uint16_t res_idx;

      if (type->flags & ResTable_type::FLAG_SPARSE) {

        auto sparse_entry = entry_offset_ptr.convert<ResTable_sparseTypeEntry>();

        offset = dtohs(sparse_entry->offset) * 4u;

        res_idx  = dtohs(sparse_entry->idx);

      } else {

        offset = dtohl(entry_offset_ptr.value());

        res_idx = entry_idx;

      }

      if (offset != ResTable_type::NO_ENTRY) {

        auto entry = type.offset(dtohl(type->entriesStart) + offset).convert<ResTable_entry>();

        if (!entry) {
@@ -394,7 +403,7 @@ base::expected<uint32_t, NullOrIOError> LoadedPackage::FindEntryByName( 
        if (dtohl(entry->key.index) == static_cast<uint32_t>(*key_idx)) {

          // The package ID will be overridden by the caller (due to runtime assignment of package

          // IDs for shared libraries).

          return make_resid(0x00, *type_idx + type_id_offset_ + 1, entry_idx);

          return make_resid(0x00, *type_idx + type_id_offset_ + 1, res_idx);

        }

      }

    }

libs/androidfw/tests/LoadedArsc_test.cpp

+32 −0
Original line number Diff line number Diff line
@@ -95,6 +95,38 @@ TEST(LoadedArscTest, LoadSparseEntryApp) { 
  ASSERT_TRUE(LoadedPackage::GetEntry(type.type, entry_index).has_value());

}



TEST(LoadedArscTest, FindSparseEntryApp) {

  std::string contents;

  ASSERT_TRUE(ReadFileFromZipToString(GetTestDataPath() + "/sparse/sparse.apk", "resources.arsc",

                                      &contents));



  std::unique_ptr<const LoadedArsc> loaded_arsc = LoadedArsc::Load(contents.data(),

                                                                   contents.length());

  ASSERT_THAT(loaded_arsc, NotNull());



  const LoadedPackage* package =

      loaded_arsc->GetPackageById(get_package_id(sparse::R::string::only_v26));

  ASSERT_THAT(package, NotNull());



  const uint8_t type_index = get_type_id(sparse::R::string::only_v26) - 1;

  const uint16_t entry_index = get_entry_id(sparse::R::string::only_v26);



  const TypeSpec* type_spec = package->GetTypeSpecByTypeIndex(type_index);

  ASSERT_THAT(type_spec, NotNull());

  ASSERT_THAT(type_spec->type_entries.size(), Ge(1u));



  // Ensure that AAPT2 sparsely encoded the v26 config as expected.

  auto type_entry = std::find_if(

    type_spec->type_entries.begin(), type_spec->type_entries.end(),

    [](const TypeSpec::TypeEntry& x) { return x.config.sdkVersion == 26; });

  ASSERT_NE(type_entry, type_spec->type_entries.end());

  ASSERT_NE(type_entry->type->flags & ResTable_type::FLAG_SPARSE, 0);



  // Test fetching a resource with only sparsely encoded configs by name.

  auto id = package->FindEntryByName(u"string", u"only_v26");

  ASSERT_EQ(id.value(), fix_package_id(sparse::R::string::only_v26, 0));

}



TEST(LoadedArscTest, LoadSharedLibrary) {

  std::string contents;

  ASSERT_TRUE(ReadFileFromZipToString(GetTestDataPath() + "/lib_one/lib_one.apk", "resources.arsc",

libs/androidfw/tests/data/sparse/R.h

+10 −9
Original line number Diff line number Diff line
@@ -27,21 +27,22 @@ struct R { 
  struct integer {

    enum : uint32_t {

      foo_0 = 0x7f010000,

      foo_1 = 0x7f010000,

      foo_2 = 0x7f010000,

      foo_3 = 0x7f010000,

      foo_4 = 0x7f010000,

      foo_5 = 0x7f010000,

      foo_6 = 0x7f010000,

      foo_7 = 0x7f010000,

      foo_8 = 0x7f010000,

      foo_9 = 0x7f010000,

      foo_1 = 0x7f010001,

      foo_2 = 0x7f010002,

      foo_3 = 0x7f010003,

      foo_4 = 0x7f010004,

      foo_5 = 0x7f010005,

      foo_6 = 0x7f010006,

      foo_7 = 0x7f010007,

      foo_8 = 0x7f010008,

      foo_9 = 0x7f010009,

    };

  };



  struct string {

    enum : uint32_t {

      foo_999 = 0x7f0203e7,

      only_v26 = 0x7f0203e8

    };

  };

};

libs/androidfw/tests/data/sparse/gen_strings.sh

+2 −0
Original line number Diff line number Diff line
@@ -14,5 +14,7 @@ do 
    fi

done

echo "</resources>" >> $OUTPUT_default



echo "  <string name=\"only_v26\">only v26</string>" >> $OUTPUT_v26

echo "</resources>" >> $OUTPUT_v26