Fix memory issues in ebpfsvc

Signed-off-by: Dave Thaler <[email protected]>

.gitmodules

@@ -4,7 +4,6 @@
 [submodule "external/ubpf"]
 	path = external/ubpf
 	url = https://github.com/iovisor/ubpf.git
-	branch = memory
 [submodule "external/bpftool"]
 	path = external/bpftool
 	url = https://github.com/dthaler/bpftool-1.git

ebpfsvc/rpc_api.cpp

@@ -23,10 +23,14 @@ ebpf_server_verify_and_load_program(
     if (info->instruction_count == 0) {
         return EBPF_INVALID_ARGUMENT;
     }
+    *logs = nullptr;
+    *logs_size = 0;
 
     // Set the handle of program being verified in thread-local storage.
     set_program_under_verification(reinterpret_cast<ebpf_handle_t>(info->program_handle));
 
+    const char* ebpf_logs = nullptr;
+    uint32_t ebpf_logs_size = 0;
     result = ebpf_verify_and_load_program(
         &info->program_type,
         reinterpret_cast<ebpf_handle_t>(info->program_handle),
@@ -36,8 +40,19 @@ ebpf_server_verify_and_load_program(
         info->handle_map,
         info->instruction_count,
         reinterpret_cast<ebpf_inst*>(info->instructions),
-        const_cast<const char**>(logs),
-        logs_size);
+        &ebpf_logs,
+        &ebpf_logs_size);
+
+    if (ebpf_logs) {
+        // The ebpf_logs buffer was allocated by the ebpf allocator whereas we
+        // must return a string allocated by the MIDL allocator.
+        *logs = (char*)MIDL_user_allocate(ebpf_logs_size);
+        if (*logs) {
+            memcpy(*logs, ebpf_logs, ebpf_logs_size);
+            ebpf_free((void*)ebpf_logs);
+            *logs_size = ebpf_logs_size;
+        }
+    }
 
     ebpf_clear_thread_local_storage();
     return result;

libs/service/verifier_service.cpp

@@ -60,7 +60,7 @@ verify_byte_code(
         info.type = get_program_type_windows(*program_type);
     } catch (std::runtime_error e) {
         error << "error: " << e.what();
-        *error_message = allocate_string(error.str());
+        *error_message = allocate_string(error.str(), error_message_size);
         return EBPF_VERIFICATION_FAILED;
     }