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[idl_parser] Validate force_align on all possible paths (#6430)

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* [idl_parser] Validate `force_align` on all possible paths

- added validation of `force_align` for `Vector`.
- added assertion to `flatbuffers::PreAlign` method

These changes should resolve following oss-fuzz issues:
- 6275816289861632
- 5713529908887552
- 4761242994606080

* size_t problem on Mac

* Fix review notes
This commit is contained in:
Vladimir Glavnyy
2021-02-11 02:37:16 +07:00
committed by GitHub
parent 6f3e45eca1
commit fee095410b
5 changed files with 39 additions and 14 deletions
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41
src/idl_parser.cpp
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@@ -1458,6 +1458,23 @@ void SimpleQsort(T *begin, T *end, size_t width, F comparator, S swapper) {
SimpleQsort(r, end, width, comparator, swapper);
}
CheckedError Parser::ParseAlignAttribute(const std::string &align_constant,
size_t min_align, size_t *align) {
// Use uint8_t to avoid problems with size_t==`unsigned long` on LP64.
uint8_t align_value;
if (StringToNumber(align_constant.c_str(), &align_value) &&
VerifyAlignmentRequirements(static_cast<size_t>(align_value),
min_align)) {
*align = align_value;
return NoError();
}
return Error("unexpected force_align value '" + align_constant +
"', alignment must be a power of two integer ranging from the "
"type\'s natural alignment " +
NumToString(min_align) + " to " +
NumToString(FLATBUFFERS_MAX_ALIGNMENT));
}
CheckedError Parser::ParseVector(const Type &type, uoffset_t *ovalue,
FieldDef *field, size_t fieldn) {
uoffset_t count = 0;
@@ -1470,13 +1487,14 @@ CheckedError Parser::ParseVector(const Type &type, uoffset_t *ovalue,
});
ECHECK(err);
const auto *force_align = field->attributes.Lookup("force_align");
const size_t align =
force_align ? static_cast<size_t>(atoi(force_align->constant.c_str()))
: 1;
const size_t len = count * InlineSize(type) / InlineAlignment(type);
const size_t elemsize = InlineAlignment(type);
if (align > 1) { builder_.ForceVectorAlignment(len, elemsize, align); }
const auto force_align = field->attributes.Lookup("force_align");
if (force_align) {
size_t align;
ECHECK(ParseAlignAttribute(force_align->constant, 1, &align));
if (align > 1) { builder_.ForceVectorAlignment(len, elemsize, align); }
}
builder_.StartVector(len, elemsize);
for (uoffset_t i = 0; i < count; i++) {
@@ -2457,17 +2475,12 @@ CheckedError Parser::ParseDecl() {
struct_def->attributes.Lookup("original_order") == nullptr && !fixed;
EXPECT('{');
while (token_ != '}') ECHECK(ParseField(*struct_def));
auto force_align = struct_def->attributes.Lookup("force_align");
if (fixed) {
const auto force_align = struct_def->attributes.Lookup("force_align");
if (force_align) {
auto align = static_cast<size_t>(atoi(force_align->constant.c_str()));
if (force_align->type.base_type != BASE_TYPE_INT ||
align < struct_def->minalign || align > FLATBUFFERS_MAX_ALIGNMENT ||
align & (align - 1))
return Error(
"force_align must be a power of two integer ranging from the"
"struct\'s natural alignment to " +
NumToString(FLATBUFFERS_MAX_ALIGNMENT));
size_t align;
ECHECK(ParseAlignAttribute(force_align->constant, struct_def->minalign,
&align));
struct_def->minalign = align;
}
if (!struct_def->bytesize) return Error("size 0 structs not allowed");