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=-10.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT 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 62279C2BB54 for ; Wed, 8 Apr 2020 01:40:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 36C9020747 for ; Wed, 8 Apr 2020 01:40:21 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="WDFsVUMZ" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726609AbgDHBkU (ORCPT ); Tue, 7 Apr 2020 21:40:20 -0400 Received: from us-smtp-2.mimecast.com ([207.211.31.81]:23415 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726417AbgDHBkU (ORCPT ); Tue, 7 Apr 2020 21:40:20 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1586310018; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=7b3hN2sSbkSm2D93h3QJ554a9zb0gmfcgA7NY6J8BVs=; b=WDFsVUMZ5B67/BNddzXFOD0Ywuv+GyOf9xqeSrhY//XXLxgpeVp/Uco/R/bkuBzeI8DGYa EwtnqBp9lizFNBfualesKuzIfFAINSOajMxcY98bUIjJ+ZvlUQPXAt+FoouEAhehlqcMMi ToayLY1MFyIohggAMEyaAwb/N92suFs= Received: from mail-qt1-f198.google.com (mail-qt1-f198.google.com [209.85.160.198]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-7-PA3XN0rTO0CLDRyS_XR0Fg-1; Tue, 07 Apr 2020 21:40:17 -0400 X-MC-Unique: PA3XN0rTO0CLDRyS_XR0Fg-1 Received: by mail-qt1-f198.google.com with SMTP id f56so4951241qte.18 for ; Tue, 07 Apr 2020 18:40:16 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=7b3hN2sSbkSm2D93h3QJ554a9zb0gmfcgA7NY6J8BVs=; b=YwfSJpkj9jxYqQYklAnDMkEtp8ZxI1/P1bSpWPQh3EeVtNZeWv69YzZxuQf4+xPD87 XyxEc0cBef3F5XvOasHtJ6HCgij9Ts1r0EWHMOBMlKTEodrNvNz3s5SBZSedAaMDrx8i MbjgYm0tG/9gqVgwHDHnIDFcvkUx5El9LJhB1cZylnHwo1aX6b6rF+C1BmMa3NGsDAe5 bdzEgNBbz1NCajMXS4usX9wh44dHxUFrb4dnLFK/kwZwztPt3j62UeHyKfvNMprH9qwB Tl+O+rKHQQ3xuZ2S5PLYFNr9Z8g6yOZ350t/qg6BGpqg4aKJ/0phBaqTKhOXbH/YMM5p 2uyw== X-Gm-Message-State: AGi0PuYC7XzDiEC2PWRmzkQ/3l8o5q0+GsHHDako49z5d0C7UkBGJtQI 9ntpamxRC9XQfrjyycCDFZF0aAijen33ozNaYB4rvV/SHYfKNtZ7Jj+iPL/1GMasYyDTWgwYxAr DVeowg92PXobFMpLZl9Aoa9+F X-Received: by 2002:ac8:27a9:: with SMTP id w38mr5008091qtw.112.1586310016214; Tue, 07 Apr 2020 18:40:16 -0700 (PDT) X-Google-Smtp-Source: APiQypKiDdfbU3ZlDmMw5zsuDQ3egIlmUEykfE0Bx/gD1U+WuGauQrVFK6YiY93u5z4zZQ9aM9zH4A== X-Received: by 2002:ac8:27a9:: with SMTP id w38mr5008079qtw.112.1586310015979; Tue, 07 Apr 2020 18:40:15 -0700 (PDT) Received: from xz-x1.hitronhub.home ([2607:9880:19c0:32::3]) by smtp.gmail.com with ESMTPSA id a186sm18438740qkg.2.2020.04.07.18.40.14 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 07 Apr 2020 18:40:15 -0700 (PDT) From: Peter Xu To: linux-kernel@vger.kernel.org, Linus Torvalds , linux-mm@kvack.org Cc: Andrew Morton , peterx@redhat.com, syzbot+693dc11fcb53120b5559@syzkaller.appspotmail.com Subject: [PATCH 1/2] mm/mempolicy: Allow lookup_node() to handle fatal signal Date: Tue, 7 Apr 2020 21:40:09 -0400 Message-Id: <20200408014010.80428-2-peterx@redhat.com> X-Mailer: git-send-email 2.24.1 In-Reply-To: <20200408014010.80428-1-peterx@redhat.com> References: <20200408014010.80428-1-peterx@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org lookup_node() uses gup to pin the page and get node information. It checks against ret>=0 assuming the page will be filled in. However it's also possible that gup will return zero, for example, when the thread is quickly killed with a fatal signal. Teach lookup_node() to gracefully return an error -EFAULT if it happens. Meanwhile, initialize "page" to NULL to avoid potential risk of exploiting the pointer. Reported-by: syzbot+693dc11fcb53120b5559@syzkaller.appspotmail.com Fixes: 4426e945df58 ("mm/gup: allow VM_FAULT_RETRY for multiple times") Signed-off-by: Peter Xu --- mm/mempolicy.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/mm/mempolicy.c b/mm/mempolicy.c index 5fb427aed612..c7ca6a808fb1 100644 --- a/mm/mempolicy.c +++ b/mm/mempolicy.c @@ -897,12 +897,15 @@ static void get_policy_nodemask(struct mempolicy *p, nodemask_t *nodes) static int lookup_node(struct mm_struct *mm, unsigned long addr) { - struct page *p; + struct page *p = NULL; int err; int locked = 1; err = get_user_pages_locked(addr & PAGE_MASK, 1, 0, &p, &locked); - if (err >= 0) { + if (err == 0) { + /* E.g. GUP interrupted by fatal signal */ + err = -EFAULT; + } else if (err > 0) { err = page_to_nid(p); put_page(p); } -- 2.24.1