From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C5667C388F9 for ; Thu, 22 Oct 2020 19:27:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7FEE8223BF for ; Thu, 22 Oct 2020 19:27:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2508036AbgJVT1b (ORCPT ); Thu, 22 Oct 2020 15:27:31 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51446 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2506002AbgJVT1a (ORCPT ); Thu, 22 Oct 2020 15:27:30 -0400 Received: from ZenIV.linux.org.uk (zeniv.linux.org.uk [IPv6:2002:c35c:fd02::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7B305C0613CE; Thu, 22 Oct 2020 12:27:30 -0700 (PDT) Received: from viro by ZenIV.linux.org.uk with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1kVgF8-006RYP-BX; Thu, 22 Oct 2020 19:27:22 +0000 Date: Thu, 22 Oct 2020 20:27:22 +0100 From: Al Viro To: Nick Desaulniers Cc: Arnd Bergmann , David Laight , Christoph Hellwig , David Hildenbrand , Greg KH , "kernel-team@android.com" , Andrew Morton , Jens Axboe , David Howells , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" , "linux-mips@vger.kernel.org" , "linux-parisc@vger.kernel.org" , "linuxppc-dev@lists.ozlabs.org" , "linux-s390@vger.kernel.org" , "sparclinux@vger.kernel.org" , "linux-block@vger.kernel.org" , "linux-scsi@vger.kernel.org" , "linux-fsdevel@vger.kernel.org" , "linux-aio@kvack.org" , "io-uring@vger.kernel.org" , "linux-arch@vger.kernel.org" , "linux-mm@kvack.org" , "netdev@vger.kernel.org" , "keyrings@vger.kernel.org" , "linux-security-module@vger.kernel.org" Subject: Re: Buggy commit tracked to: "Re: [PATCH 2/9] iov_iter: move rw_copy_check_uvector() into lib/iov_iter.c" Message-ID: <20201022192722.GW3576660@ZenIV.linux.org.uk> References: <5fd6003b-55a6-2c3c-9a28-8fd3a575ca78@redhat.com> <20201022132342.GB8781@lst.de> <8f1fff0c358b4b669d51cc80098dbba1@AcuMS.aculab.com> <20201022192458.GV3576660@ZenIV.linux.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201022192458.GV3576660@ZenIV.linux.org.uk> Sender: Al Viro Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org On Thu, Oct 22, 2020 at 08:24:58PM +0100, Al Viro wrote: > On Thu, Oct 22, 2020 at 12:04:52PM -0700, Nick Desaulniers wrote: > > > Passing an `unsigned long` as an `unsigned int` does no such > > narrowing: https://godbolt.org/z/TvfMxe (same vice-versa, just tail > > calls, no masking instructions). > > So if rw_copy_check_uvector() is inlined into import_iovec() (looking > > at the mainline@1028ae406999), then children calls of > > `rw_copy_check_uvector()` will be interpreting the `nr_segs` register > > unmodified, ie. garbage in the upper 32b. > > FWIW, > > void f(unsinged long v) s/unsinged/unsigned/, obviously...