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Bound declared element counts against remaining buffer in from_wire #235

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Bound declared element counts against remaining buffer in from_wire #235

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12 changes: 12 additions & 0 deletions src/dataencode.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -153,6 +153,9 @@ void from_wire(Buffer& buf, std::vector<FieldDesc>& descs, TypeStore& cache, uns
{
auto& fld = descs.back();

// bound child count to bytes remaining before reserving (see note in pvaproto.h)
if(nfld.size > (size_t)buf.size())
nfld.size = buf.size();
fld.miter.reserve(nfld.size);
}

Expand Down Expand Up @@ -618,6 +621,9 @@ void from_wire_field(Buffer& buf, TypeStore& ctxt, const FieldDesc* desc, const
case TypeCode::StructA:{
Size alen{};
from_wire(buf, alen);
// bound element count to bytes remaining before allocating (see note in pvaproto.h)
if(alen.size > (size_t)buf.size())
alen.size = buf.size();
shared_array<Value> arr(alen.size);
std::shared_ptr<const FieldDesc> etype(store->top->desc,
&desc->members[0]); // alias
Expand All @@ -635,6 +641,9 @@ void from_wire_field(Buffer& buf, TypeStore& ctxt, const FieldDesc* desc, const
case TypeCode::UnionA: {
Size alen{};
from_wire(buf, alen);
// bound element count to bytes remaining before allocating (see note in pvaproto.h)
if(alen.size > (size_t)buf.size())
alen.size = buf.size();
shared_array<Value> arr(alen.size);
auto cdesc = &desc->members[0];

Expand Down Expand Up @@ -667,6 +676,9 @@ void from_wire_field(Buffer& buf, TypeStore& ctxt, const FieldDesc* desc, const
case TypeCode::AnyA:{
Size alen{};
from_wire(buf, alen);
// bound element count to bytes remaining before allocating (see note in pvaproto.h)
if(alen.size > (size_t)buf.size())
alen.size = buf.size();
shared_array<Value> arr(alen.size);

for(auto& elem : arr) {
Expand Down
5 changes: 5 additions & 0 deletions src/pvaproto.h
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Original file line number Diff line number Diff line change
Expand Up @@ -528,6 +528,11 @@ void from_wire(Buffer& buf, shared_array<const void>& varr)
{
Size slen{};
from_wire(buf, slen);
// A valid array cannot contain more elements than there are bytes remaining in the
// message (each element occupies >= 1 byte on the wire). Bound the declared count
// before allocating so a crafted count cannot drive an unbounded allocation.
if(slen.size > (size_t)buf.size())
slen.size = buf.size();
shared_array<E> arr(slen.size);

if(std::is_pod<C>::value) {
Expand Down