Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932474AbcKGREj (ORCPT ); Mon, 7 Nov 2016 12:04:39 -0500 Received: from mail-it0-f67.google.com ([209.85.214.67]:34809 "EHLO mail-it0-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753403AbcKGREf (ORCPT ); Mon, 7 Nov 2016 12:04:35 -0500 MIME-Version: 1.0 In-Reply-To: References: <7c0dfa3b2ea712bd2cc6343445f263815b81918f.1478525307.git.jslaby@suse.cz> From: Linus Torvalds Date: Mon, 7 Nov 2016 08:45:59 -0800 X-Google-Sender-Auth: HrUDkbxMQhCm26_EzOiNrnQ5qY0 Message-ID: Subject: Re: [PATCH 3.12 69/72] Revert "fix minor infoleak in get_user_ex()" To: Jiri Slaby , Greg KH Cc: stable , Linux Kernel Mailing List , Al Viro Content-Type: multipart/mixed; boundary=001a113e39f63abb190540b8c21c Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2813 Lines: 50 --001a113e39f63abb190540b8c21c Content-Type: text/plain; charset=UTF-8 So a patch something like this might be a safe way to fix the potential infoleak in older kernels. THIS IS UNTESTED. It's a very obvious patch, though, so if it compiles it probably works. It just initializes the output variable with 0 in the inline asm description, instead of doing it in the exception handler. It will generate slightly worse code (a few unnecessary ALU operations), but it doesn't have any interactions with the exception handler implementation. Linus --001a113e39f63abb190540b8c21c Content-Type: text/plain; charset=US-ASCII; name="patch.diff" Content-Disposition: attachment; filename="patch.diff" Content-Transfer-Encoding: base64 X-Attachment-Id: f_iv8aueam0 IGFyY2gveDg2L2luY2x1ZGUvYXNtL3VhY2Nlc3MuaCB8IDEwICsrKysrLS0tLS0KIDEgZmlsZSBj aGFuZ2VkLCA1IGluc2VydGlvbnMoKyksIDUgZGVsZXRpb25zKC0pCgpkaWZmIC0tZ2l0IGEvYXJj aC94ODYvaW5jbHVkZS9hc20vdWFjY2Vzcy5oIGIvYXJjaC94ODYvaW5jbHVkZS9hc20vdWFjY2Vz cy5oCmluZGV4IDU4MzhmYTkxMWFhMC4uYzJlMDZlZThiMjkwIDEwMDY0NAotLS0gYS9hcmNoL3g4 Ni9pbmNsdWRlL2FzbS91YWNjZXNzLmgKKysrIGIvYXJjaC94ODYvaW5jbHVkZS9hc20vdWFjY2Vz cy5oCkBAIC0zMjEsNyArMzIxLDcgQEAgZG8gewkJCQkJCQkJCVwKICNkZWZpbmUgX19nZXRfdXNl cl9hc21fdTY0KHgsIHB0ciwgcmV0dmFsLCBlcnJyZXQpIFwKIAkgX19nZXRfdXNlcl9hc20oeCwg cHRyLCByZXR2YWwsICJxIiwgIiIsICI9ciIsIGVycnJldCkKICNkZWZpbmUgX19nZXRfdXNlcl9h c21fZXhfdTY0KHgsIHB0cikgXAotCSBfX2dldF91c2VyX2FzbV9leCh4LCBwdHIsICJxIiwgIiIs ICI9ciIpCisJIF9fZ2V0X3VzZXJfYXNtX2V4KHgsIHB0ciwgInEiLCAiIiwgIj0mciIpCiAjZW5k aWYKIAogI2RlZmluZSBfX2dldF91c2VyX3NpemUoeCwgcHRyLCBzaXplLCByZXR2YWwsIGVycnJl dCkJCQlcCkBAIC0zNjQsMTMgKzM2NCwxMyBAQCBkbyB7CQkJCQkJCQkJXAogCV9fY2hrX3VzZXJf cHRyKHB0cik7CQkJCQkJXAogCXN3aXRjaCAoc2l6ZSkgewkJCQkJCQlcCiAJY2FzZSAxOgkJCQkJ CQkJXAotCQlfX2dldF91c2VyX2FzbV9leCh4LCBwdHIsICJiIiwgImIiLCAiPXEiKTsJCVwKKwkJ X19nZXRfdXNlcl9hc21fZXgoeCwgcHRyLCAiYiIsICJiIiwgIj0mcSIpOwkJXAogCQlicmVhazsJ CQkJCQkJXAogCWNhc2UgMjoJCQkJCQkJCVwKLQkJX19nZXRfdXNlcl9hc21fZXgoeCwgcHRyLCAi dyIsICJ3IiwgIj1yIik7CQlcCisJCV9fZ2V0X3VzZXJfYXNtX2V4KHgsIHB0ciwgInciLCAidyIs ICI9JnIiKTsJCVwKIAkJYnJlYWs7CQkJCQkJCVwKIAljYXNlIDQ6CQkJCQkJCQlcCi0JCV9fZ2V0 X3VzZXJfYXNtX2V4KHgsIHB0ciwgImwiLCAiayIsICI9ciIpOwkJXAorCQlfX2dldF91c2VyX2Fz bV9leCh4LCBwdHIsICJsIiwgImsiLCAiPSZyIik7CQlcCiAJCWJyZWFrOwkJCQkJCQlcCiAJY2Fz ZSA4OgkJCQkJCQkJXAogCQlfX2dldF91c2VyX2FzbV9leF91NjQoeCwgcHRyKTsJCQkJXApAQCAt Mzg0LDcgKzM4NCw3IEBAIGRvIHsJCQkJCQkJCQlcCiAJYXNtIHZvbGF0aWxlKCIxOgltb3YiaXR5 cGUiICUxLCUicnR5cGUiMFxuIgkJXAogCQkgICAgICIyOlxuIgkJCQkJCVwKIAkJICAgICBfQVNN X0VYVEFCTEVfRVgoMWIsIDJiKQkJCQlcCi0JCSAgICAgOiBsdHlwZSh4KSA6ICJtIiAoX19tKGFk ZHIpKSkKKwkJICAgICA6IGx0eXBlKHgpIDogIm0iIChfX20oYWRkcikpLCAiMCIgKDApKQogCiAj ZGVmaW5lIF9fcHV0X3VzZXJfbm9jaGVjayh4LCBwdHIsIHNpemUpCQkJXAogKHsJCQkJCQkJCVwK --001a113e39f63abb190540b8c21c--