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Verifier Refinements (#7490)

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This commit is contained in:
Derek Bailey
2022-08-29 19:21:42 -07:00
committed by GitHub
parent bf5d23230a
commit b190ce11b0
1 changed files with 20 additions and 35 deletions
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55
include/flatbuffers/verifier.h
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@@ -34,39 +34,25 @@ class Verifier FLATBUFFERS_FINAL_CLASS {
bool check_alignment = true; bool check_alignment = true;
// If true, run verifier on nested flatbuffers // If true, run verifier on nested flatbuffers
bool check_nested_flatbuffers = true; bool check_nested_flatbuffers = true;
// Manually implemented constructors for compilers that can't figure it out.
Options() = default;
Options(uoffset_t d, uoffset_t t, bool a, bool n)
: max_depth(d),
max_tables(t),
check_alignment(a),
check_nested_flatbuffers(n) {}
}; };
Verifier(const uint8_t *const buf, const size_t buf_len, const Options opts) explicit Verifier(const uint8_t *const buf, const size_t buf_len,
: buf_(buf), const Options &opts)
size_(buf_len), : buf_(buf), size_(buf_len), opts_(opts) {
opts_(opts),
upper_bound_(0),
depth_(0),
num_tables_(0),
flex_reuse_tracker_(nullptr) {
FLATBUFFERS_ASSERT(size_ < FLATBUFFERS_MAX_BUFFER_SIZE); FLATBUFFERS_ASSERT(size_ < FLATBUFFERS_MAX_BUFFER_SIZE);
} }
// Deprecated API, please construct with Verifier::Options. // Deprecated API, please construct with Verifier::Options.
Verifier(const uint8_t *const buf, const size_t buf_len, Verifier(const uint8_t *const buf, const size_t buf_len,
const uoffset_t _max_depth = 64, const uoffset_t max_depth = 64, const uoffset_t max_tables = 1000000,
const uoffset_t _max_tables = 1000000, const bool check_alignment = true)
const bool _check_alignment = true) : Verifier(buf, buf_len, [&] {
: Verifier(buf, buf_len, Options opts;
{ opts.max_depth = max_depth;
_max_depth, opts.max_tables = max_tables;
_max_tables, opts.check_alignment = check_alignment;
_check_alignment, return opts;
true, }()) {}
}) {}
// Central location where any verification failures register. // Central location where any verification failures register.
bool Check(const bool ok) const { bool Check(const bool ok) const {
@@ -153,8 +139,8 @@ class Verifier FLATBUFFERS_FINAL_CLASS {
const auto veco = static_cast<size_t>(vec - buf_); const auto veco = static_cast<size_t>(vec - buf_);
// Check we can read the size field. // Check we can read the size field.
if (!Verify<uoffset_t>(veco)) return false; if (!Verify<uoffset_t>(veco)) return false;
// Check the whole array. If this is a string, the byte past the array // Check the whole array. If this is a string, the byte past the array must
// must be 0. // be 0.
const auto size = ReadScalar<uoffset_t>(vec); const auto size = ReadScalar<uoffset_t>(vec);
const auto max_elems = FLATBUFFERS_MAX_BUFFER_SIZE / elem_size; const auto max_elems = FLATBUFFERS_MAX_BUFFER_SIZE / elem_size;
if (!Check(size < max_elems)) if (!Check(size < max_elems))
@@ -277,9 +263,8 @@ class Verifier FLATBUFFERS_FINAL_CLASS {
} }
// Called at the start of a table to increase counters measuring data // Called at the start of a table to increase counters measuring data
// structure depth and amount, and possibly bails out with false if // structure depth and amount, and possibly bails out with false if limits set
// limits set by the constructor have been hit. Needs to be balanced // by the constructor have been hit. Needs to be balanced with EndTable().
// with EndTable().
bool VerifyComplexity() { bool VerifyComplexity() {
depth_++; depth_++;
num_tables_++; num_tables_++;
@@ -320,11 +305,11 @@ class Verifier FLATBUFFERS_FINAL_CLASS {
const size_t size_; const size_t size_;
const Options opts_; const Options opts_;
mutable size_t upper_bound_; mutable size_t upper_bound_ = 0;
uoffset_t depth_; uoffset_t depth_ = 0;
uoffset_t num_tables_; uoffset_t num_tables_ = 0;
std::vector<uint8_t> *flex_reuse_tracker_; std::vector<uint8_t> *flex_reuse_tracker_ = nullptr;
}; };
} // namespace flatbuffers } // namespace flatbuffers