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 3B888C388F7 for ; Thu, 22 Oct 2020 19:29:09 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 708F424658 for ; Thu, 22 Oct 2020 19:29:07 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 708F424658 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=zeniv.linux.org.uk Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from bilbo.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 4CHHV93p1mzDr0v for ; Fri, 23 Oct 2020 06:29:05 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; spf=none (no SPF record) smtp.mailfrom=ftp.linux.org.uk (client-ip=2002:c35c:fd02::1; helo=zeniv.linux.org.uk; envelope-from=viro@ftp.linux.org.uk; receiver=) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=zeniv.linux.org.uk Received: from ZenIV.linux.org.uk (zeniv.linux.org.uk [IPv6:2002:c35c:fd02::1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4CHHSN4gTZzDqvj for ; Fri, 23 Oct 2020 06:27:32 +1100 (AEDT) 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 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> X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: "linux-aio@kvack.org" , David Hildenbrand , "linux-mips@vger.kernel.org" , David Howells , "linux-mm@kvack.org" , "keyrings@vger.kernel.org" , "sparclinux@vger.kernel.org" , Christoph Hellwig , "linux-arch@vger.kernel.org" , "linux-s390@vger.kernel.org" , "linux-scsi@vger.kernel.org" , "kernel-team@android.com" , Arnd Bergmann , "linux-block@vger.kernel.org" , "io-uring@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , Jens Axboe , "linux-parisc@vger.kernel.org" , Greg KH , "linux-kernel@vger.kernel.org" , "linux-security-module@vger.kernel.org" , David Laight , "netdev@vger.kernel.org" , "linux-fsdevel@vger.kernel.org" , Andrew Morton , "linuxppc-dev@lists.ozlabs.org" Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" 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...