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=-8.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=ham 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 CFA1AC3A59F for ; Mon, 26 Aug 2019 15:11:05 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 9F92F2080C for ; Mon, 26 Aug 2019 15:11:05 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9F92F2080C Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.cz Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 4AEDF6B059E; Mon, 26 Aug 2019 11:11:05 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 437D96B059F; Mon, 26 Aug 2019 11:11:05 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 34DC96B05A0; Mon, 26 Aug 2019 11:11:05 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0035.hostedemail.com [216.40.44.35]) by kanga.kvack.org (Postfix) with ESMTP id 0A2036B059E for ; Mon, 26 Aug 2019 11:11:05 -0400 (EDT) Received: from smtpin04.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with SMTP id AF6D7180AD801 for ; Mon, 26 Aug 2019 15:11:04 +0000 (UTC) X-FDA: 75864916848.04.stove74_2670772533d39 X-HE-Tag: stove74_2670772533d39 X-Filterd-Recvd-Size: 2945 Received: from mx1.suse.de (mx2.suse.de [195.135.220.15]) by imf47.hostedemail.com (Postfix) with ESMTP for ; Mon, 26 Aug 2019 15:11:04 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id B4C73AEF6; Mon, 26 Aug 2019 15:11:01 +0000 (UTC) Subject: Re: [PATCH] mm/migrate: initialize pud_entry in migrate_vma() To: Ralph Campbell , linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org, stable@vger.kernel.org, =?UTF-8?B?SsOpcsO0bWUgR2xpc3Nl?= , Andrew Morton References: <20190719233225.12243-1-rcampbell@nvidia.com> From: Vlastimil Babka Message-ID: <0d639edf-9f96-c170-4920-d64c2891d35d@suse.cz> Date: Mon, 26 Aug 2019 17:11:01 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <20190719233225.12243-1-rcampbell@nvidia.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: quoted-printable 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 7/20/19 1:32 AM, Ralph Campbell wrote: > When CONFIG_MIGRATE_VMA_HELPER is enabled, migrate_vma() calls > migrate_vma_collect() which initializes a struct mm_walk but > didn't initialize mm_walk.pud_entry. (Found by code inspection) > Use a C structure initialization to make sure it is set to NULL. >=20 > Fixes: 8763cb45ab967 ("mm/migrate: new memory migration helper for use = with > device memory") > Cc: stable@vger.kernel.org > Signed-off-by: Ralph Campbell > Cc: "J=C3=A9r=C3=B4me Glisse" > Cc: Andrew Morton So this bug can manifest by some garbage address on stack being called, r= ight? I wonder, how comes it didn't actually happen yet? > --- > mm/migrate.c | 17 +++++++---------- > 1 file changed, 7 insertions(+), 10 deletions(-) >=20 > diff --git a/mm/migrate.c b/mm/migrate.c > index 515718392b24..a42858d8e00b 100644 > --- a/mm/migrate.c > +++ b/mm/migrate.c > @@ -2340,16 +2340,13 @@ static int migrate_vma_collect_pmd(pmd_t *pmdp, > static void migrate_vma_collect(struct migrate_vma *migrate) > { > struct mmu_notifier_range range; > - struct mm_walk mm_walk; > - > - mm_walk.pmd_entry =3D migrate_vma_collect_pmd; > - mm_walk.pte_entry =3D NULL; > - mm_walk.pte_hole =3D migrate_vma_collect_hole; > - mm_walk.hugetlb_entry =3D NULL; > - mm_walk.test_walk =3D NULL; > - mm_walk.vma =3D migrate->vma; > - mm_walk.mm =3D migrate->vma->vm_mm; > - mm_walk.private =3D migrate; > + struct mm_walk mm_walk =3D { > + .pmd_entry =3D migrate_vma_collect_pmd, > + .pte_hole =3D migrate_vma_collect_hole, > + .vma =3D migrate->vma, > + .mm =3D migrate->vma->vm_mm, > + .private =3D migrate, > + }; > =20 > mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, NULL, mm_walk.mm= , > migrate->start, >=20