fix(uptime_proof): validate version-list sizes before fixed-array writes

[raw391]

The Proof::Proof(const std::string& serialized_proof) deserializer at src/cryptonote_core/uptime_proof.cpp:44-89 reads three version lists (v, sv, lv) from a bt-encoded peer-supplied blob into three fixed-size 3-element arrays (version[], storage_server_version[], belnet_version[]) without first checking that each bt_list has 3 entries:

const bt_list& bt_version = var::get<bt_list>(bt_proof.at("v"));
int k = 0;
for (bt_value const &i: bt_version){
  version[k++] = static_cast<uint16_t>(get_int<unsigned>(i));
}

A peer that sends a proof whose v list has more than 3 entries walks past the end of version[] into adjacent members of the Proof struct on the heap (the constructor is invoked via std::make_unique at cryptonote_core.cpp:1994). The constructor runs before any signature check downstream.

Patch adds an exact-size guard before each write loop, and wraps the make_unique call site in try/catch so a malformed proof becomes a rejected proof rather than a propagating exception:

     const bt_list& bt_version = var::get<bt_list>(bt_proof.at("v"));
+    if (bt_version.size() != version.size())
+      throw std::invalid_argument("uptime proof: invalid mnode_version list size");
     int k = 0;
     for (bt_value const &i: bt_version){
       version[k++] = static_cast<uint16_t>(get_int<unsigned>(i));
     }

(Plus matching guards for sv and lv.)

   bool core::handle_btencoded_uptime_proof(...)
   {
     crypto::x25519_public_key pkey = {};
-    auto proof = std::make_unique<uptime_proof::Proof>(req.proof);
+    std::unique_ptr<uptime_proof::Proof> proof;
+    try
+    {
+      proof = std::make_unique<uptime_proof::Proof>(req.proof);
+    }
+    catch (const std::exception &e)
+    {
+      MWARNING("Failed to parse uptime proof: " << e.what());
+      return false;
+    }
     proof->sig = tools::make_from_guts<crypto::signature>(req.sig);

Exact-match (!=) rather than > because a short list would leave the trailing array slots uninitialized.