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,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 9B8D6C432C0 for ; Tue, 3 Dec 2019 22:56:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 63D87217D7 for ; Tue, 3 Dec 2019 22:56:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1575413794; bh=Z8aICHbrIM347DJ5/MBMdz5RRjHh6rlblcjp0EeSyYs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=h5yoXoA+XN5tlqTlWYbt3L9Iq9ALFEGopeRAdTu5jk4tYdeX5imVyY8TgzU5UZzzG xHvswBWPwpSoffQXoSiYFjeijLpQYW1yJoQECjP6+j21G0i5+92Ao1Sr6jtFjb3UdH ti1euJaV0wF2dUdWID0HKfTa1+LhLBsCrMhSvMFg= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730444AbfLCW4c (ORCPT ); Tue, 3 Dec 2019 17:56:32 -0500 Received: from mail.kernel.org ([198.145.29.99]:51530 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730434AbfLCW42 (ORCPT ); Tue, 3 Dec 2019 17:56:28 -0500 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 B505520866; Tue, 3 Dec 2019 22:56:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1575413788; bh=Z8aICHbrIM347DJ5/MBMdz5RRjHh6rlblcjp0EeSyYs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=1CEQIKwYK3eOc16aO7G2BlbA0DK3N8Ea1bo8P2ukMElPkMFRe0sN1YCEIRv5m7kNM MiT/E4m8ytrxvZT++2i0hsVpiIO16hKmOmjnltwq8/bkionWHHJoD0eaH+niD6PNHE q+vJR6Ti2Y0MH0YMpWTP8Ze5HGaHLOl+ULGNzCmU= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Vlastimil Babka , Sasha Levin Subject: [PATCH 4.19 263/321] mm, gup: add missing refcount overflow checks on s390 Date: Tue, 3 Dec 2019 23:35:29 +0100 Message-Id: <20191203223440.811248012@linuxfoundation.org> X-Mailer: git-send-email 2.24.0 In-Reply-To: <20191203223427.103571230@linuxfoundation.org> References: <20191203223427.103571230@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 From: Vlastimil Babka The mainline commit 8fde12ca79af ("mm: prevent get_user_pages() from overflowing page refcount") was backported to 4.19.y stable as commit d972ebbf42ba. The backport however missed that in 4.19, there are several arch-specific gup.c versions with fast gup implementations, so these do not prevent refcount overflow. This stable-only commit fixes the s390 version, and is based on the backport in SUSE SLES/openSUSE 4.12-based kernels. The remaining architectures with own gup.c are sparc, mips, sh. It's unlikely the known overflow scenario based on FUSE, which needs 140GB of RAM, is a problem for those architectures, and I don't feel confident enough to patch them. Signed-off-by: Vlastimil Babka Signed-off-by: Sasha Levin --- arch/s390/mm/gup.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/arch/s390/mm/gup.c b/arch/s390/mm/gup.c index 2809d11c7a283..9b5b866d8adf1 100644 --- a/arch/s390/mm/gup.c +++ b/arch/s390/mm/gup.c @@ -39,7 +39,8 @@ static inline int gup_pte_range(pmd_t *pmdp, pmd_t pmd, unsigned long addr, VM_BUG_ON(!pfn_valid(pte_pfn(pte))); page = pte_page(pte); head = compound_head(page); - if (!page_cache_get_speculative(head)) + if (unlikely(WARN_ON_ONCE(page_ref_count(head) < 0) + || !page_cache_get_speculative(head))) return 0; if (unlikely(pte_val(pte) != pte_val(*ptep))) { put_page(head); @@ -77,7 +78,8 @@ static inline int gup_huge_pmd(pmd_t *pmdp, pmd_t pmd, unsigned long addr, refs++; } while (addr += PAGE_SIZE, addr != end); - if (!page_cache_add_speculative(head, refs)) { + if (unlikely(WARN_ON_ONCE(page_ref_count(head) < 0) + || !page_cache_add_speculative(head, refs))) { *nr -= refs; return 0; } @@ -151,7 +153,8 @@ static int gup_huge_pud(pud_t *pudp, pud_t pud, unsigned long addr, refs++; } while (addr += PAGE_SIZE, addr != end); - if (!page_cache_add_speculative(head, refs)) { + if (unlikely(WARN_ON_ONCE(page_ref_count(head) < 0) + || !page_cache_add_speculative(head, refs))) { *nr -= refs; return 0; } -- 2.20.1