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Commit 04390376 authored by Steven Moreland's avatar Steven Moreland
Browse files

avoid extra release of unowned objects in Parcel error path 

Another bug due to a huge amount of complexity in the Parcel
implementation.

Bug: 203847542
Test: added testcase fails on device w/o Parcel.cpp fix, and it passes
  on a device with the fix
Change-Id: I34411675687cb3d18bffa082984ebdf308e1c1a6
parent f367330f

libs/binder/Parcel.cpp

+5 −3
Original line number Diff line number Diff line
@@ -2181,12 +2181,14 @@ void Parcel::ipcSetDataReference(const uint8_t* data, size_t dataSize, 
              type == BINDER_TYPE_FD)) {

            // We should never receive other types (eg BINDER_TYPE_FDA) as long as we don't support

            // them in libbinder. If we do receive them, it probably means a kernel bug; try to

            // recover gracefully by clearing out the objects, and releasing the objects we do

            // know about.

            // recover gracefully by clearing out the objects.

            android_errorWriteLog(0x534e4554, "135930648");

            android_errorWriteLog(0x534e4554, "203847542");

            ALOGE("%s: unsupported type object (%" PRIu32 ") at offset %" PRIu64 "\n",

                  __func__, type, (uint64_t)offset);

            releaseObjects();



            // WARNING: callers of ipcSetDataReference need to make sure they

            // don't rely on mObjectsSize in their release_func.

            mObjectsSize = 0;

            break;

        }

libs/binder/tests/binderLibTest.cpp

+43 −3
Original line number Diff line number Diff line
@@ -112,7 +112,7 @@ enum BinderLibTestTranscationCode { 
    BINDER_LIB_TEST_NOP_TRANSACTION_WAIT,

    BINDER_LIB_TEST_GETPID,

    BINDER_LIB_TEST_ECHO_VECTOR,

    BINDER_LIB_TEST_REJECT_BUF,

    BINDER_LIB_TEST_REJECT_OBJECTS,

    BINDER_LIB_TEST_CAN_GET_SID,

};
@@ -1166,13 +1166,53 @@ TEST_F(BinderLibTest, BufRejected) { 
    memcpy(parcelData, &obj, sizeof(obj));

    data.setDataSize(sizeof(obj));



    EXPECT_EQ(data.objectsCount(), 1);



    // Either the kernel should reject this transaction (if it's correct), but

    // if it's not, the server implementation should return an error if it

    // finds an object in the received Parcel.

    EXPECT_THAT(server->transact(BINDER_LIB_TEST_REJECT_BUF, data, &reply),

    EXPECT_THAT(server->transact(BINDER_LIB_TEST_REJECT_OBJECTS, data, &reply),

                Not(StatusEq(NO_ERROR)));

}



TEST_F(BinderLibTest, WeakRejected) {

    Parcel data, reply;

    sp<IBinder> server = addServer();

    ASSERT_TRUE(server != nullptr);



    auto binder = sp<BBinder>::make();

    wp<BBinder> wpBinder(binder);

    flat_binder_object obj{

            .hdr = {.type = BINDER_TYPE_WEAK_BINDER},

            .flags = 0,

            .binder = reinterpret_cast<uintptr_t>(wpBinder.get_refs()),

            .cookie = reinterpret_cast<uintptr_t>(wpBinder.unsafe_get()),

    };

    data.setDataCapacity(1024);

    // Write a bogus object at offset 0 to get an entry in the offset table

    data.writeFileDescriptor(0);

    EXPECT_EQ(data.objectsCount(), 1);

    uint8_t *parcelData = const_cast<uint8_t *>(data.data());

    // And now, overwrite it with the weak binder

    memcpy(parcelData, &obj, sizeof(obj));

    data.setDataSize(sizeof(obj));



    // a previous bug caused other objects to be released an extra time, so we

    // test with an object that libbinder will actually try to release

    EXPECT_EQ(OK, data.writeStrongBinder(sp<BBinder>::make()));



    EXPECT_EQ(data.objectsCount(), 2);



    // send it many times, since previous error was memory corruption, make it

    // more likely that the server crashes

    for (size_t i = 0; i < 100; i++) {

        EXPECT_THAT(server->transact(BINDER_LIB_TEST_REJECT_OBJECTS, data, &reply),

                    StatusEq(BAD_VALUE));

    }



    EXPECT_THAT(server->pingBinder(), StatusEq(NO_ERROR));

}



TEST_F(BinderLibTest, GotSid) {

    sp<IBinder> server = addServer();
@@ -1566,7 +1606,7 @@ public: 
                reply->writeUint64Vector(vector);

                return NO_ERROR;

            }

            case BINDER_LIB_TEST_REJECT_BUF: {

            case BINDER_LIB_TEST_REJECT_OBJECTS: {

                return data.objectsCount() == 0 ? BAD_VALUE : NO_ERROR;

            }

            case BINDER_LIB_TEST_CAN_GET_SID: {