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=-6.9 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS autolearn=unavailable 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 87D4FC46460 for ; Wed, 29 May 2019 07:09:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 60FC421721 for ; Wed, 29 May 2019 07:09:42 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="p49ChQ13" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726454AbfE2HJl (ORCPT ); Wed, 29 May 2019 03:09:41 -0400 Received: from mail-lj1-f195.google.com ([209.85.208.195]:46123 "EHLO mail-lj1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725948AbfE2HJl (ORCPT ); Wed, 29 May 2019 03:09:41 -0400 Received: by mail-lj1-f195.google.com with SMTP id m15so1295175ljg.13 for ; Wed, 29 May 2019 00:09:39 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=0hmEt8XBAszMFOt/NHrMak9iR4Ln+O6rhKTThaepQX0=; b=p49ChQ13CkTgafcWq6Mx8FOk/3a/AeGpi05o5uxn0TRjMP7yQKQUwXpN1bbkt6bsUL BOp03/oTIkbFDCJgo8EFfNE0dDIo9i7rKReMyFNF1dZ/M1Tga6IFPJqU6RNwQ9ztAKEi kVPSOn09OJUcGey1NdvjzyLfUrSxYu2LvzfPCvj/ykDhrPxYoFREu8hf7+IFKkVuznxg wzzsesZ5sTsck6PUx8smbK+YfBzvT0kXI2A1La8N2CmQUuFn1pR26ai5oseyyE1t//7M Jp5OBTnFMGRX4xsL05DMLjI183G/vREXuSDRD9tAOSzGCVHCv3Od22rktQlI1NPK0/Wh hWLQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=0hmEt8XBAszMFOt/NHrMak9iR4Ln+O6rhKTThaepQX0=; b=n+VW0VvtJ6xS5GzeRNo78U9H48ms2BOpcKA3Ce/G0hwPVIysTFDqh4GJ8JrbuALCRk SzwpvlBcbdOOGK8uGU8JAKEnu8N743BVl5N4yyCPXbQHmA7au3artTfsXnPZOQrgRcJb HiStFb/CZ3evEBC3MS5vWYciYw+GbHouZfPy+T9T2ZYq6aru+mjwvRabmanspJIFaB42 6QlSjhm5W+fwWFugPRYEXYGTm0B+uyHrhbM4HF4LBDQrUWoF8SK3MLkVTPVlgdOJox1Y GS/QBXwEHNpOrl2aNmtRMPAPJxmHgT0g+RiAASLneFIybQcvZWE5vIGY9EVs5cjXSvOh u/OA== X-Gm-Message-State: APjAAAX1qow/Q0UkQGFG+K1SUpJa1ZAL2/DWXccs1tRaHqouwSpXyKjy VvV08yIzXvQ2n5nLToSyTdU5kIB+31Gm30fQ7iI= X-Google-Smtp-Source: APXvYqzPybpE3leNNpeYsxD/syHNbqQB4AamoUBooFN787Z8X3jpIs8qqKLWY3d8qJDJTDSMGWjIGZogbhlUDWuIO+4= X-Received: by 2002:a2e:9dc6:: with SMTP id x6mr1537784ljj.27.1559113778900; Wed, 29 May 2019 00:09:38 -0700 (PDT) MIME-Version: 1.0 References: <20190528193004.GA7744@gmail.com> In-Reply-To: <20190528193004.GA7744@gmail.com> From: Souptick Joarder Date: Wed, 29 May 2019 12:39:27 +0530 Message-ID: Subject: Re: [PATCH] mm: Fail when offset == num in first check of vm_map_pages_zero() To: Miguel Ojeda Cc: Matthew Wilcox , Peter Zijlstra , =?UTF-8?B?SsOpcsO0bWUgR2xpc3Nl?= , "Aneesh Kumar K.V" , Huang Ying , open list , Linux-MM Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, May 29, 2019 at 1:38 AM Miguel Ojeda wrote: > > If the user asks us for offset == num, we should already fail in the > first check, i.e. the one testing for offsets beyond the object. > > At the moment, we are failing on the second test anyway, > since count cannot be 0. Still, to agree with the comment of the first > test, we should first there. I think, we need to cc linux-mm. > > Signed-off-by: Miguel Ojeda > --- > mm/memory.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/mm/memory.c b/mm/memory.c > index ddf20bd0c317..74cf8b0ce353 100644 > --- a/mm/memory.c > +++ b/mm/memory.c > @@ -1547,7 +1547,7 @@ static int __vm_map_pages(struct vm_area_struct *vma, struct page **pages, > int ret, i; > > /* Fail if the user requested offset is beyond the end of the object */ > - if (offset > num) > + if (offset >= num) > return -ENXIO; > > /* Fail if the user requested size exceeds available object size */ > -- > 2.17.1 >