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=-9.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,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 EE967C76186 for ; Mon, 29 Jul 2019 19:55:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BA55021655 for ; Mon, 29 Jul 2019 19:55:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1564430130; bh=lRxTkn5ni5yFAnlGU5me0IUymEJm74FXaiFGQ5FWTWQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=YxRF3A8pMyRtd/zHAkKfMYecMYBCfGzr0Wbgoo/FZtV6Z1+91r74MGiusWQ+X+9jO moSfh4ok4dqbkf1Jrw5cUCNXEbKOqoDe5w+8VqaFCFC1uAR+lsoyf8LQRZB7NRo2Wy EONg4YokUenxMt+LXZRdPqsNJ3aqLRpS8bvGlF7s= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2404220AbfG2Tz3 (ORCPT ); Mon, 29 Jul 2019 15:55:29 -0400 Received: from mail.kernel.org ([198.145.29.99]:48222 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2403997AbfG2TzZ (ORCPT ); Mon, 29 Jul 2019 15:55:25 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 564F721655; Mon, 29 Jul 2019 19:55:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1564430124; bh=lRxTkn5ni5yFAnlGU5me0IUymEJm74FXaiFGQ5FWTWQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=2H/iHirPzYkcIkDFhI449nYPgbyF9Iv9AbF6q31OOnO2IdD7Co9fAFHNKBGh4hx1d dXr+xS7zSbcrtjcC84jdnImlnkeKhjK6sMu4SzVDicoVE/HFYhH3i3F+P5e80EeAb5 pay/+r+645PFPQFQZXj6A51R6T0h2g/Y85vUS+gI= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Andy Lutomirski , Kees Cook , Andrew Morton , Florian Weimer , Jann Horn , Linus Torvalds , Sasha Levin Subject: [PATCH 5.2 154/215] mm/gup.c: remove some BUG_ONs from get_gate_page() Date: Mon, 29 Jul 2019 21:22:30 +0200 Message-Id: <20190729190806.462204986@linuxfoundation.org> X-Mailer: git-send-email 2.22.0 In-Reply-To: <20190729190739.971253303@linuxfoundation.org> References: <20190729190739.971253303@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org [ Upstream commit b5d1c39f34d1c9bca0c4b9ae2e339fbbe264a9c7 ] If we end up without a PGD or PUD entry backing the gate area, don't BUG -- just fail gracefully. It's not entirely implausible that this could happen some day on x86. It doesn't right now even with an execute-only emulated vsyscall page because the fixmap shares the PUD, but the core mm code shouldn't rely on that particular detail to avoid OOPSing. Link: http://lkml.kernel.org/r/a1d9f4efb75b9d464e59fd6af00104b21c58f6f7.1561610798.git.luto@kernel.org Signed-off-by: Andy Lutomirski Reviewed-by: Kees Cook Reviewed-by: Andrew Morton Cc: Florian Weimer Cc: Jann Horn Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin --- mm/gup.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/mm/gup.c b/mm/gup.c index 22855ff0b448..d2c14fc4b5d4 100644 --- a/mm/gup.c +++ b/mm/gup.c @@ -585,11 +585,14 @@ static int get_gate_page(struct mm_struct *mm, unsigned long address, pgd = pgd_offset_k(address); else pgd = pgd_offset_gate(mm, address); - BUG_ON(pgd_none(*pgd)); + if (pgd_none(*pgd)) + return -EFAULT; p4d = p4d_offset(pgd, address); - BUG_ON(p4d_none(*p4d)); + if (p4d_none(*p4d)) + return -EFAULT; pud = pud_offset(p4d, address); - BUG_ON(pud_none(*pud)); + if (pud_none(*pud)) + return -EFAULT; pmd = pmd_offset(pud, address); if (!pmd_present(*pmd)) return -EFAULT; -- 2.20.1