From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 65AEA4F30D1; Mon, 19 Oct 2026 13:03:48 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1792415031; cv=none; b=g7YkWwzgsqd1+6/jLOyUxHqChNfv55XtuV2TmIQ2wjlxQI4iI92SIH1+b9T5Q0AnkBmtRBxYbh1yvzcnit2sP6Ly1IA8rTfyKTojzE0jAZIjjZkaMihCemnNy+OIw/901eshnuEZNMQe9oZleQVNXLkKHZan8njoBEFlIT1MwFg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1792415031; c=relaxed/simple; bh=4Taeq9YK0PITmj3CBagWrbfjN37RzWn6zgZk3bA+mlc=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=qtO3QitKWZnSCIM0b7FaMZTtJlXBozhKi3bGzSi/4BXXpk6yEgRVG5D0JHb3XzgbOo2nfZPI8O869fe+KFvB8SFlxzHNRiyB3m0Uly9weRXdVBonh5aX/Puu5MKGGOX3ITLw4ncf29cJ9XUlXsp2HqJr608gglVdAlTZErvoNjs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=M/D3bv1+; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="M/D3bv1+" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 37F521F000C4; Mon, 19 Oct 2026 13:03:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1792415028; bh=6LlZu7xXOV37Ar4P8MV/lQtWWvsy/NiMXBi7QZ4/VXo=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=M/D3bv1+sxBITlSR0jLZD5AxIjlMk1ykOAVEDwKcBALMnEUPmCotLmz6EBIwbSi2u jrjq1HUVJH1qMqYEgfuYPPpxubN8Y0R0vFSUPqrKXaMOWsnJhw0pXZeMmgRozKHtiB Uu3lUSVgh21bdBcIU7qT4lTXkeo3pQoBGz549MCYPBSKQO3smRNJV0LHJ0Y4wgmwKj p21lKMiBiyqTE4i4snXR6S7MgQUXvT619uwnzoXzK3lJYbhA+3bEU1qxiPn4SX79mF dSHjJZHO3JPd1EBYg+yOBn4Jm4cQEg9n7oKM/0jO+tfEgFXNyt0PHxhvVOUvoA50IK /CX4UMT0DOnsQ== Message-ID: <493158de-7b76-45ca-9d71-ad8981242c12@kernel.org> Date: Mon, 19 Oct 2026 15:03:43 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] selftests/x86: Fix userfaultfd test for shadow stack rejection To: "Ning, Hongyu" , x86@kernel.org, shuah@kernel.org, rick.p.edgecombe@intel.com Cc: tglx@kernel.org, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, hpa@zytor.com, ljs@kernel.org, rppt@kernel.org, akpm@linux-foundation.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, hongyu.ning@intel.com, jolsa@kernel.org, dwindsor@gmail.com References: <3b3e0a35-e664-40ab-84ad-afa3e31e3aea@linux.intel.com> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 10/19/26 03:03, Ning, Hongyu wrote: > Commit 3c58f641e813 ("userfaultfd: prevent registration of special > VMAs") prevents userfaultfd registration on shadow stack VMAs to avoid > bypassing shadow stack protections through UFFDIO_COPY. > > The existing shadow stack selftest still expects UFFDIO_REGISTER to > succeed and uses UFFDIO_COPY to populate the shadow stack. This causes > the selftest to fail on Kernels containing this security fix. > > Update the selftest to verify that UFFDIO_REGISTER rejects shadow stack > VMAs with EINVAL. Remove the obsolete userfaultfd fault handling thread > and UFFDIO_COPY test path. > > Tested on: Intel shadow stack capable x86_64 platform > > Before fix: > [FAIL] Userfaultfd test with return code 1 > > After fix: > [OK] Userfaultfd rejects shadow stack registration (EINVAL) Interesting, so we wouldn't be able to snapshot+restore an app that uses shadow stacks. @Mike: I assume that's not a concern for CRIU etc, right? > > Fixes: 3c58f641e813 ("userfaultfd: prevent registration of special VMAs") > > Signed-off-by: Hongyu Ning Acked-by: David Hildenbrand (Arm) -- Cheers, David