From d0c99b279d5bb38fb2f6d6fe998489149f8ca004 Mon Sep 17 00:00:00 2001
From: Abhijeet Prasad <aprasad@sentry.io>
Date: Wed, 22 Mar 2023 12:10:02 +0100
Subject: [PATCH] Be more defensive when recursing through error cause chain

---
 packages/react/src/errorboundary.tsx       | 18 ++++++++--
 packages/react/test/errorboundary.test.tsx | 39 ++++++++++++++++++++++
 2 files changed, 54 insertions(+), 3 deletions(-)

diff --git a/packages/react/src/errorboundary.tsx b/packages/react/src/errorboundary.tsx
index d7312fdeffbb..377eedc7fd47 100644
--- a/packages/react/src/errorboundary.tsx
+++ b/packages/react/src/errorboundary.tsx
@@ -67,10 +67,22 @@ const INITIAL_STATE = {
 };
 
 function setCause(error: Error & { cause?: Error }, cause: Error): void {
-  if (error.cause) {
-    return setCause(error.cause, cause);
+  const seenErrors = new Map<Error, boolean>();
+
+  function recurse(error: Error & { cause?: Error }, cause: Error): void {
+    // If we've already seen the error, there is a recursive loop somewhere in the error's
+    // cause chain. Let's just bail out then to prevent a stack overflow.
+    if (seenErrors.has(error)) {
+      return;
+    }
+    if (error.cause) {
+      seenErrors.set(error, true);
+      return recurse(error.cause, cause);
+    }
+    error.cause = cause;
   }
-  error.cause = cause;
+
+  recurse(error, cause);
 }
 
 /**
diff --git a/packages/react/test/errorboundary.test.tsx b/packages/react/test/errorboundary.test.tsx
index 3f9284d03efa..251112242313 100644
--- a/packages/react/test/errorboundary.test.tsx
+++ b/packages/react/test/errorboundary.test.tsx
@@ -341,6 +341,45 @@ describe('ErrorBoundary', () => {
       expect(cause.message).toEqual(thirdError.message);
     });
 
+    it('handles when `error.cause` is recursive', () => {
+      const mockOnError = jest.fn();
+
+      function CustomBam(): JSX.Element {
+        const firstError = new Error('bam');
+        const secondError = new Error('bam2');
+        // @ts-ignore Need to set cause on error
+        firstError.cause = secondError;
+        // @ts-ignore Need to set cause on error
+        secondError.cause = firstError;
+        throw firstError;
+      }
+
+      render(
+        <TestApp fallback={<p>You have hit an error</p>} onError={mockOnError} errorComp={<CustomBam />}>
+          <h1>children</h1>
+        </TestApp>,
+      );
+
+      expect(mockOnError).toHaveBeenCalledTimes(0);
+      expect(mockCaptureException).toHaveBeenCalledTimes(0);
+
+      const btn = screen.getByTestId('errorBtn');
+      fireEvent.click(btn);
+
+      expect(mockCaptureException).toHaveBeenCalledTimes(1);
+      expect(mockCaptureException).toHaveBeenLastCalledWith(expect.any(Error), {
+        contexts: { react: { componentStack: expect.any(String) } },
+      });
+
+      expect(mockOnError.mock.calls[0][0]).toEqual(mockCaptureException.mock.calls[0][0]);
+
+      const error = mockCaptureException.mock.calls[0][0];
+      const cause = error.cause;
+      // We need to make sure that recursive error.cause does not cause infinite loop
+      expect(cause.stack).not.toEqual(mockCaptureException.mock.calls[0][1].contexts.react.componentStack);
+      expect(cause.name).not.toContain('React ErrorBoundary');
+    });
+
     it('calls `beforeCapture()` when an error occurs', () => {
       const mockBeforeCapture = jest.fn();