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=-10.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable 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 3AD17C76188 for ; Fri, 19 Jul 2019 04:07:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 14F4F218A6 for ; Fri, 19 Jul 2019 04:07:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1563509223; bh=CHUtUjcoZCmdIpRrpFG+/0VQUcEan2l3QkxxlFRqon0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=BdJlh8OrqU+KfkirXlbitm1hJGi4aSzBSN4BT/gvsVskj0TGV4pLjF9EUaSNFrVtA lxaVS5uepIwh6ZZ/urMlvGjGJhBFH4roXb4K5Qggg4qwsOO74BrEocMsp7rvcX9RBw zB7eTEdpayxeYPL93Rz3UoMvRyXkEesgwY5Xc3a8= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732465AbfGSEHB (ORCPT ); Fri, 19 Jul 2019 00:07:01 -0400 Received: from mail.kernel.org ([198.145.29.99]:40300 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732403AbfGSEGy (ORCPT ); Fri, 19 Jul 2019 00:06:54 -0400 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id BC53721873; Fri, 19 Jul 2019 04:06:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1563509213; bh=CHUtUjcoZCmdIpRrpFG+/0VQUcEan2l3QkxxlFRqon0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=cwI8doY6BUeacgHioVlGSNw5ZLKGRjmfT3rwprqv11m70iCRU9N7Lb1kbkDMdfH7N EkqHrjrAF4Kicy+A9LxAMsrYrlyBaEq2aVceABwUFJyMuLoTzoXY9hQaFQGG2mqw68 QRiTR54s/VuWMW2xIKkttJbRNM4mkBw4orDzXXak= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Andy Lutomirski , Kees Cook , Andrew Morton , Florian Weimer , Jann Horn , Linus Torvalds , Sasha Levin , linux-mm@kvack.org Subject: [PATCH AUTOSEL 5.1 130/141] mm/gup.c: remove some BUG_ONs from get_gate_page() Date: Fri, 19 Jul 2019 00:02:35 -0400 Message-Id: <20190719040246.15945-130-sashal@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190719040246.15945-1-sashal@kernel.org> References: <20190719040246.15945-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Andy Lutomirski [ 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 60d759f4e4b5..de2e506d4aae 100644 --- a/mm/gup.c +++ b/mm/gup.c @@ -479,11 +479,14 @@ 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