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Merge "libsnapshot: fix integer overflow when calculating sector id."

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TreeHugger Robot 2022-08-02 18:59:04 +00:00 committed by Android (Google) Code Review
commit 814825fac6
1 changed files with 17 additions and 4 deletions
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21
fs_mgr/libsnapshot/partition_cow_creator.cpp
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@ -131,15 +131,28 @@ bool OptimizeSourceCopyOperation(const InstallOperation& operation, InstallOpera
return is_optimized;
}
void WriteExtent(DmSnapCowSizeCalculator* sc, const chromeos_update_engine::Extent& de,
bool WriteExtent(DmSnapCowSizeCalculator* sc, const chromeos_update_engine::Extent& de,
unsigned int sectors_per_block) {
const auto block_boundary = de.start_block() + de.num_blocks();
for (auto b = de.start_block(); b < block_boundary; ++b) {
for (unsigned int s = 0; s < sectors_per_block; ++s) {
const auto sector_id = b * sectors_per_block + s;
// sector_id = b * sectors_per_block + s;
uint64_t block_start_sector_id;
if (__builtin_mul_overflow(b, sectors_per_block, &block_start_sector_id)) {
LOG(ERROR) << "Integer overflow when calculating sector id (" << b << " * "
<< sectors_per_block << ")";
return false;
}
uint64_t sector_id;
if (__builtin_add_overflow(block_start_sector_id, s, &sector_id)) {
LOG(ERROR) << "Integer overflow when calculating sector id ("
<< block_start_sector_id << " + " << s << ")";
return false;
}
sc->WriteSector(sector_id);
}
}
return true;
}
std::optional<uint64_t> PartitionCowCreator::GetCowSize() {
@ -167,7 +180,7 @@ std::optional<uint64_t> PartitionCowCreator::GetCowSize() {
// Allocate space for extra extents (if any). These extents are those that can be
// used for error corrections or to store verity hash trees.
for (const auto& de : extra_extents) {
WriteExtent(&sc, de, sectors_per_block);
if (!WriteExtent(&sc, de, sectors_per_block)) return std::nullopt;
}
if (update == nullptr) return sc.cow_size_bytes();
@ -182,7 +195,7 @@ std::optional<uint64_t> PartitionCowCreator::GetCowSize() {
}
for (const auto& de : written_op->dst_extents()) {
WriteExtent(&sc, de, sectors_per_block);
if (!WriteExtent(&sc, de, sectors_per_block)) return std::nullopt;
}
}