The analysis of the provided commit 2835554ffe37ac4ba3b794e6d6c0bfd1dc8db301 clearly indicates the source of the open redirect vulnerability. The patch was applied to the EditLayoutMVCActionCommand.java file, specifically within the doProcessAction method. Before the fix, the code directly retrieved the redirect parameter from the user request using ParamUtil.getString(actionRequest, "redirect") and used it without validation. This is the vulnerable action. The fix introduces a call to _portal.escapeRedirect(), which is designed to prevent malicious redirects. Therefore, the doProcessAction function is the exact location of the vulnerability, as it processes the untrusted input that leads to the redirect.