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[192.55.52.93]) by mx.google.com with ESMTPS id d10si18129081plr.307.2019.06.03.07.59.00 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 03 Jun 2019 07:59:00 -0700 (PDT) Received-SPF: pass (google.com: domain of ira.weiny@intel.com designates 192.55.52.93 as permitted sender) client-ip=192.55.52.93; Authentication-Results: mx.google.com; spf=pass (google.com: domain of ira.weiny@intel.com designates 192.55.52.93 as permitted sender) smtp.mailfrom=ira.weiny@intel.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=intel.com X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False Received: from fmsmga003.fm.intel.com ([10.253.24.29]) by fmsmga102.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 03 Jun 2019 07:59:00 -0700 X-ExtLoop1: 1 Received: from iweiny-desk2.sc.intel.com ([10.3.52.157]) by FMSMGA003.fm.intel.com with ESMTP; 03 Jun 2019 07:58:59 -0700 Date: Mon, 3 Jun 2019 08:00:08 -0700 From: Ira Weiny To: Pingfan Liu Cc: linux-mm@kvack.org, Andrew Morton , Mike Rapoport , Dan Williams , Matthew Wilcox , John Hubbard , "Aneesh Kumar K.V" , Keith Busch , linux-kernel@vger.kernel.org Subject: Re: [PATCHv2 1/2] mm/gup: fix omission of check on FOLL_LONGTERM in get_user_pages_fast() Message-ID: <20190603150007.GA26623@iweiny-DESK2.sc.intel.com> References: <1559543653-13185-1-git-send-email-kernelfans@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1559543653-13185-1-git-send-email-kernelfans@gmail.com> User-Agent: Mutt/1.11.1 (2018-12-01) 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 Mon, Jun 03, 2019 at 02:34:12PM +0800, Pingfan Liu wrote: > As for FOLL_LONGTERM, it is checked in the slow path > __gup_longterm_unlocked(). But it is not checked in the fast path, which > means a possible leak of CMA page to longterm pinned requirement through > this crack. > > Place a check in the fast path. > > Signed-off-by: Pingfan Liu Reviewed-by: Ira Weiny > Cc: Ira Weiny > Cc: Andrew Morton > Cc: Mike Rapoport > Cc: Dan Williams > Cc: Matthew Wilcox > Cc: John Hubbard > Cc: "Aneesh Kumar K.V" > Cc: Keith Busch > Cc: linux-kernel@vger.kernel.org > --- > mm/gup.c | 24 ++++++++++++++++++++++++ > 1 file changed, 24 insertions(+) > > diff --git a/mm/gup.c b/mm/gup.c > index f173fcb..6fe2feb 100644 > --- a/mm/gup.c > +++ b/mm/gup.c > @@ -2196,6 +2196,29 @@ static int __gup_longterm_unlocked(unsigned long start, int nr_pages, > return ret; > } > > +#if defined(CONFIG_CMA) > +static inline int reject_cma_pages(int nr_pinned, unsigned int gup_flags, > + struct page **pages) > +{ > + if (unlikely(gup_flags & FOLL_LONGTERM)) { > + int i = 0; > + > + for (i = 0; i < nr_pinned; i++) > + if (is_migrate_cma_page(pages[i])) { > + put_user_pages(pages + i, nr_pinned - i); > + return i; > + } > + } > + return nr_pinned; > +} > +#else > +static inline int reject_cma_pages(int nr_pinned, unsigned int gup_flags, > + struct page **pages) > +{ > + return nr_pinned; > +} > +#endif > + > /** > * get_user_pages_fast() - pin user pages in memory > * @start: starting user address > @@ -2236,6 +2259,7 @@ int get_user_pages_fast(unsigned long start, int nr_pages, > ret = nr; > } > > + nr = reject_cma_pages(nr, gup_flags, pages); > if (nr < nr_pages) { > /* Try to get the remaining pages with get_user_pages */ > start += nr << PAGE_SHIFT; > -- > 2.7.5 >