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[209.85.220.65]) by mx.google.com with SMTPS id r26sor2427184ljb.10.2019.05.29.00.09.39 for (Google Transport Security); Wed, 29 May 2019 00:09:39 -0700 (PDT) Received-SPF: pass (google.com: domain of jrdr.linux@gmail.com designates 209.85.220.65 as permitted sender) client-ip=209.85.220.65; Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b=p49ChQ13; spf=pass (google.com: domain of jrdr.linux@gmail.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=jrdr.linux@gmail.com; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com 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-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" X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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 >