From ba38f3becce7d1283585c73d796eb47d72bbbd30 Mon Sep 17 00:00:00 2001
From: Radoslav Gerganov <rgerganov@gmail.com>
Date: Fri, 27 Mar 2026 10:59:35 +0200
Subject: [PATCH] rpc : proper handling of data pointers to CPU buffers
 (#21030)

The compute graph may contain tensors pointing to CPU buffers. In these
cases the buffer address is serialized as 0 and sent over the wire.
However, the data pointer is serialized as-is and this prevents proper
validation on the server side. This patches fixes this by serializing
the data pointer as 0 for non-RPC buffers and doing proper validation on
the server side.

closes: #21006
---
 ggml/src/ggml-rpc/ggml-rpc.cpp | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/ggml/src/ggml-rpc/ggml-rpc.cpp b/ggml/src/ggml-rpc/ggml-rpc.cpp
index 0ed2c0dce6..16f6abdffd 100644
--- a/ggml/src/ggml-rpc/ggml-rpc.cpp
+++ b/ggml/src/ggml-rpc/ggml-rpc.cpp
@@ -589,8 +589,10 @@ static rpc_tensor serialize_tensor(const ggml_tensor * tensor) {
         ggml_backend_buffer_t buffer = tensor->buffer;
         ggml_backend_rpc_buffer_context * ctx = (ggml_backend_rpc_buffer_context *)buffer->context;
         result.buffer = ctx != nullptr ? ctx->remote_ptr : 0;
+        result.data = reinterpret_cast<uint64_t>(tensor->data);
     } else {
         result.buffer = 0;
+        result.data   = 0;
     }
     for (uint32_t i = 0; i < GGML_MAX_DIMS; i++) {
         result.ne[i] = tensor->ne[i];
@@ -606,7 +608,6 @@ static rpc_tensor serialize_tensor(const ggml_tensor * tensor) {
     }
     result.view_src = reinterpret_cast<uint64_t>(tensor->view_src);
     result.view_offs = tensor->view_offs;
-    result.data = reinterpret_cast<uint64_t>(tensor->data);
 
     // Avoid sending uninitialized data over the wire
     memset(result.name, 0, sizeof(result.name));
@@ -1443,9 +1444,11 @@ ggml_tensor * rpc_server::create_node(uint64_t id,
     const rpc_tensor * tensor = it_ptr->second;
 
     struct ggml_tensor * result = deserialize_tensor(ctx, tensor);
-    if (result == nullptr || result->buffer == nullptr) {
-        GGML_LOG_ERROR("[%s] invalid tensor: null %s (id=%" PRIu64 ")\n",
-                       __func__, result == nullptr ? "tensor" : "buffer", id);
+    if (result == nullptr) {
+        return nullptr;
+    }
+    if (result->buffer == nullptr && result->data != nullptr) {
+        GGML_LOG_ERROR("[%s] invalid data ptr", __func__);
         return nullptr;
     }
     tensor_map[id] = result;