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Propagate failure of MetadataBuilder creation in CreateUpdateSnapshots

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In a device with malformed metadata, the MetadataBuilder returns a
nullptr that may cause segmentation faults when using the builder.
Fix by handling the nullptr exception in CreateUpdateSnapshot and
propagating the error to its caller.

Bug: n/a
Test: libsnapshot_test
Change-Id: Ie9148a552cf4bb223ab8d54b1d30d2b13d92bb22
Signed-off-by: Alessio Balsini <balsini@google.com>
This commit is contained in:
Alessio Balsini 2020-01-30 16:28:05 +00:00
parent fce02741d3
commit fb5de5bc8f
2 changed files with 15 additions and 0 deletions
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9
fs_mgr/libsnapshot/snapshot.cpp
View file

@ -1957,8 +1957,17 @@ Return SnapshotManager::CreateUpdateSnapshots(const DeltaArchiveManifest& manife
auto current_super = device_->GetSuperDevice(current_slot);
auto current_metadata = MetadataBuilder::New(opener, current_super, current_slot);
if (current_metadata == nullptr) {
LOG(ERROR) << "Cannot create metadata builder.";
return Return::Error();
}
auto target_metadata =
MetadataBuilder::NewForUpdate(opener, current_super, current_slot, target_slot);
if (target_metadata == nullptr) {
LOG(ERROR) << "Cannot create target metadata builder.";
return Return::Error();
}
// Delete partitions with target suffix in |current_metadata|. Otherwise,
// partition_cow_creator recognizes these left-over partitions as used space.

6
fs_mgr/libsnapshot/snapshot_test.cpp
View file

@ -793,6 +793,7 @@ class SnapshotUpdateTest : public SnapshotTest {
// Initialize source partition metadata using |manifest_|.
src_ = MetadataBuilder::New(*opener_, "super", 0);
ASSERT_NE(src_, nullptr);
ASSERT_TRUE(FillFakeMetadata(src_.get(), manifest_, "_a"));
// Add sys_b which is like system_other.
ASSERT_TRUE(src_->AddGroup("group_b", kGroupSize));
@ -987,6 +988,7 @@ TEST_F(SnapshotUpdateTest, FullUpdateFlow) {
// Test that partitions prioritize using space in super.
auto tgt = MetadataBuilder::New(*opener_, "super", 1);
ASSERT_NE(tgt, nullptr);
ASSERT_NE(nullptr, tgt->FindPartition("sys_b-cow"));
ASSERT_NE(nullptr, tgt->FindPartition("vnd_b-cow"));
ASSERT_EQ(nullptr, tgt->FindPartition("prd_b-cow"));
@ -1200,7 +1202,9 @@ TEST_F(SnapshotUpdateTest, ReclaimCow) {
// Check that the old COW space is reclaimed and does not occupy space of mapped partitions.
auto src = MetadataBuilder::New(*opener_, "super", 1);
ASSERT_NE(src, nullptr);
auto tgt = MetadataBuilder::New(*opener_, "super", 0);
ASSERT_NE(tgt, nullptr);
for (const auto& cow_part_name : {"sys_a-cow", "vnd_a-cow", "prd_a-cow"}) {
auto* cow_part = tgt->FindPartition(cow_part_name);
ASSERT_NE(nullptr, cow_part) << cow_part_name << " does not exist in target metadata";
@ -1291,6 +1295,7 @@ TEST_F(SnapshotUpdateTest, MergeCannotRemoveCow) {
SetSize(vnd_, 5_MiB);
SetSize(prd_, 5_MiB);
src_ = MetadataBuilder::New(*opener_, "super", 0);
ASSERT_NE(src_, nullptr);
src_->RemoveGroupAndPartitions(group_->name() + "_a");
src_->RemoveGroupAndPartitions(group_->name() + "_b");
ASSERT_TRUE(FillFakeMetadata(src_.get(), manifest_, "_a"));
@ -1664,6 +1669,7 @@ TEST_P(FlashAfterUpdateTest, FlashSlotAfterUpdate) {
// Simulate flashing |flashed_slot|. This clears the UPDATED flag.
auto flashed_builder = MetadataBuilder::New(*opener_, "super", flashed_slot);
ASSERT_NE(flashed_builder, nullptr);
flashed_builder->RemoveGroupAndPartitions(group_->name() + flashed_slot_suffix);
flashed_builder->RemoveGroupAndPartitions(kCowGroupName);
ASSERT_TRUE(FillFakeMetadata(flashed_builder.get(), manifest_, flashed_slot_suffix));