fix(rpc): prevent division by zero in deserialize_tensor (ggml-org#20712)

rpc : prevent division by zero in deserialize_tensor

When receiving an RPC message with a deprecated tensor type (e.g., type 4 or 5 where `blck_size == 0`), `ggml_row_size()` will trigger a division by zero (SIGFPE) and crash the rpc-server. 

This patch adds a simple validation check in `deserialize_tensor` to return `nullptr` if the requested tensor type has a block size of 0.

(Note: This was originally reported via Security Advisory and maintainer suggested dropping a patch here).

* style: remove trailing whitespace

Author: y198nt

ggml/src/ggml-rpc/ggml-rpc.cpp

@@ -1162,12 +1162,18 @@ ggml_tensor * rpc_server::deserialize_tensor(struct ggml_context * ctx, const rp
         return nullptr;
     }
 
+    // Fix: Prevent division by zero if blck_size is 0 (e.g., deprecated types)
+    if (ggml_blck_size((enum ggml_type)tensor->type) == 0) {
+        GGML_LOG_ERROR("[%s] invalid tensor type received (blck_size is 0): %u\n", __func__, tensor->type);
+        return nullptr;
+    }
+
     ggml_tensor * result = ggml_new_tensor_4d(ctx, (ggml_type) tensor->type,
         tensor->ne[0], tensor->ne[1], tensor->ne[2], tensor->ne[3]);
 
     // ggml_new_tensor_4d might fail if dimensions are invalid, although less likely to crash than invalid type
     if (result == nullptr) {
-        GGML_LOG_ERROR("[%s] ggml_new_tensor_4d failed for type %u\\n", __func__, tensor->type);
+        GGML_LOG_ERROR("[%s] ggml_new_tensor_4d failed for type %u\n", __func__, tensor->type);
         return nullptr;
     }