fix(oauth): bound github-copilot OAuth response reads at 16 MiB

openclaw · vincentkoc · Jun 28, 2026 · Jun 28, 2026 · Jun 28, 2026 · Jun 28, 2026
commit 32ef926ff0e4ffc7c40da8ac387873612a89afde
diff --git a/src/llm/utils/oauth/github-copilot.test.ts b/src/llm/utils/oauth/github-copilot.test.ts
@@ -181,3 +181,85 @@ describe("GitHub Copilot OAuth model policy", () => {
     expect(cancel).toHaveBeenCalledTimes(1);
   });
 });
+
+describe("GitHub Copilot OAuth bounded reads", () => {
+  it("caps oversized OAuth JSON responses instead of buffering the full body", async () => {
+    // 18 MiB body in 1 MiB chunks exceeds the 16 MiB default cap on
+    // the shared readProviderJsonResponse reader.
+    const CHUNK = 1024 * 1024;
+    const CHUNK_COUNT = 18;
+    let pulls = 0;
+    const encoder = new TextEncoder();
+    const stream = new ReadableStream<Uint8Array>({
+      pull(controller) {
+        if (pulls >= CHUNK_COUNT) {
+          controller.close();
+          return;
+        }
+        pulls += 1;
+        controller.enqueue(encoder.encode("a".repeat(CHUNK)));
+      },
+    });
+    vi.stubGlobal(
+      "fetch",
+      vi.fn(
+        async () =>
+          new Response(stream, {
+            status: 200,
+            headers: { "Content-Type": "application/json" },
+          }),
+      ),
+    );
+
+    await expect(refreshGitHubCopilotToken("refresh-token")).rejects.toThrow(
+      "GitHub Copilot token refresh request: JSON response exceeds 16777216 bytes",
+    );
+  });
+
+  it("parses normal-size OAuth JSON responses under the byte cap", async () => {
+    vi.stubGlobal(
+      "fetch",
+      vi.fn(
+        async () =>
+          new Response(
+            JSON.stringify({
+              token: "copilot-token",
+              expires_at: Math.floor(Date.now() / 1000) + 3600,
+            }),
+            { status: 200, headers: { "Content-Type": "application/json" } },
+          ),
+      ),
+    );
+
+    const result = await refreshGitHubCopilotToken("refresh-token");
+    expect(result.access).toBe("copilot-token");
+    expect(typeof result.expires).toBe("number");
+  });
+
+  it("cancels the upstream body when the bounded reader overflows", async () => {
+    const cancel = vi.fn(async () => undefined);
+    const encoder = new TextEncoder();
+    const source = new ReadableStream<Uint8Array>({
+      pull(controller) {
+        controller.enqueue(encoder.encode("a".repeat(1024 * 1024)));
+      },
+      cancel,
+    });
+    vi.stubGlobal(
+      "fetch",
+      vi.fn(
+        async () =>
+          new Response(source, {
+            status: 200,
+            headers: { "Content-Type": "application/json" },
+          }),
+      ),
+    );
+
+    await expect(refreshGitHubCopilotToken("refresh-token")).rejects.toThrow(
+      "GitHub Copilot token refresh request",
+    );
+
+    expect(cancel).toHaveBeenCalled();
+  });
+});
diff --git a/src/llm/utils/oauth/github-copilot.ts b/src/llm/utils/oauth/github-copilot.ts
@@ -3,6 +3,10 @@
  */
 
 import { resolveTimerTimeoutMs } from "@openclaw/normalization-core/number-coercion";
+import {
+  readProviderJsonResponse,
+  readProviderTextResponse,
+} from "../../../agents/provider-http-errors.js";
 import {
   nonNegativeSecondsToSafeMilliseconds,
   positiveSecondsToSafeMilliseconds,
@@ -175,18 +179,21 @@ async function fetchResponse(
   }
 }
 
+// Shared 16 MiB bounded reader — a hostile OAuth endpoint cannot force the
+// runtime to buffer an unbounded body through `.text()` / `.json()`.
 async function fetchJson(
   url: string,
   init: RequestInit,
   operation: string,
   options: CopilotRequestOptions = {},
 ): Promise<unknown> {
   const response = await fetchResponse(url, init, operation, options);
+  const label = `GitHub Copilot ${operation}`;
   if (!response.ok) {
-    const text = await response.text();
+    const text = await readProviderTextResponse(response, label);
     throw new Error(`${response.status} ${response.statusText}: ${text}`);
   }
-  return response.json();
+  return readProviderJsonResponse(response, label);
 }
 
 async function startDeviceFlow(