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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id D5838CCA485 for ; Tue, 28 Jun 2022 11:47:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S245734AbiF1Lrs (ORCPT ); Tue, 28 Jun 2022 07:47:48 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37882 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1345359AbiF1Lr0 (ORCPT ); Tue, 28 Jun 2022 07:47:26 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B82A5240 for ; Tue, 28 Jun 2022 04:47:17 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 747E5B818E0 for ; Tue, 28 Jun 2022 11:47:16 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5E40FC341CA; Tue, 28 Jun 2022 11:47:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1656416835; bh=dKzZ/vy7HHvgx95lHEzqYt47FaFP0k+n4+nWn7QZZlU=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=adOwIr7067hKNeKFJcoiTocRHJNGaEOqofpqK5jToyY6VCO+PkuBp1vUomCAYqW5s Dj20lxK75cnFhOfiBVaEEJd9FnRiaNiT1RsKcz2ASwttMgV238cvMcv2GDNNxDWrR8 Q/YJrKT7dCrOL0oiZLZN2mqS/n4aNTMAT9r5oqB/cFxLJbH2xUVUg4qejZ83m/jv1V SJMIOpbBoLl26Ux29TePzxHxEJkMv6ygHQxb1esoRbGSef/7b9TVh6lt++EAnsevM5 mYkGulRhSVtgHnBewYX2k0z/JfVEacdGug/WnfTQ7HoHaJCDVmZyZXAJFTSy6z8jaO IaX+tfsLjsShA== Message-ID: <9b5c07c490f67b1fc35d6ec0900dfb161120ccd8.camel@kernel.org> Subject: Re: [PATCH 25/44] iov_iter_get_pages(): sanity-check arguments From: Jeff Layton To: Al Viro , linux-fsdevel@vger.kernel.org Cc: Linus Torvalds , Jens Axboe , Christoph Hellwig , Matthew Wilcox , David Howells , Dominique Martinet , Christian Brauner Date: Tue, 28 Jun 2022 07:47:12 -0400 In-Reply-To: <20220622041552.737754-25-viro@zeniv.linux.org.uk> References: <20220622041552.737754-1-viro@zeniv.linux.org.uk> <20220622041552.737754-25-viro@zeniv.linux.org.uk> Content-Type: text/plain; charset="ISO-8859-15" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.44.2 (3.44.2-1.fc36) MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Wed, 2022-06-22 at 05:15 +0100, Al Viro wrote: > zero maxpages is bogus, but best treated as "just return 0"; > NULL pages, OTOH, should be treated as a hard bug. >=20 > get rid of now completely useless checks in xarray_get_pages{,_alloc}(). >=20 > Signed-off-by: Al Viro > --- > lib/iov_iter.c | 9 ++------- > 1 file changed, 2 insertions(+), 7 deletions(-) >=20 > diff --git a/lib/iov_iter.c b/lib/iov_iter.c > index 9c25661684c6..5c985cf2858e 100644 > --- a/lib/iov_iter.c > +++ b/lib/iov_iter.c > @@ -1271,9 +1271,6 @@ static ssize_t iter_xarray_get_pages(struct iov_ite= r *i, > size_t size =3D maxsize; > loff_t pos; > =20 > - if (!size || !maxpages) > - return 0; > - > pos =3D i->xarray_start + i->iov_offset; > index =3D pos >> PAGE_SHIFT; > offset =3D pos & ~PAGE_MASK; > @@ -1365,10 +1362,11 @@ ssize_t iov_iter_get_pages(struct iov_iter *i, > =20 > if (maxsize > i->count) > maxsize =3D i->count; > - if (!maxsize) > + if (!maxsize || !maxpages) > return 0; > if (maxsize > MAX_RW_COUNT) > maxsize =3D MAX_RW_COUNT; > + BUG_ON(!pages); > =20 > if (likely(user_backed_iter(i))) { > unsigned int gup_flags =3D 0; > @@ -1441,9 +1439,6 @@ static ssize_t iter_xarray_get_pages_alloc(struct i= ov_iter *i, > size_t size =3D maxsize; > loff_t pos; > =20 > - if (!size) > - return 0; > - > pos =3D i->xarray_start + i->iov_offset; > index =3D pos >> PAGE_SHIFT; > offset =3D pos & ~PAGE_MASK; Reviewed-by: Jeff Layton