From mboxrd@z Thu Jan 1 00:00:00 1970 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754528AbdBET5g (ORCPT + 2 others); Sun, 5 Feb 2017 14:57:36 -0500 Received: from wtarreau.pck.nerim.net ([62.212.114.60]:28133 "EHLO 1wt.eu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752981AbdBETZj (ORCPT ); Sun, 5 Feb 2017 14:25:39 -0500 From: Willy Tarreau To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, linux@roeck-us.net Cc: Jann Horn , "Kirill A. Shutemov" , Vlastimil Babka , Hugh Dickins , Andrew Morton , Linus Torvalds , Willy Tarreau Subject: [PATCH 3.10 104/319] swapfile: fix memory corruption via malformed swapfile Date: Sun, 5 Feb 2017 20:18:46 +0100 Message-Id: <1486322541-8206-5-git-send-email-w@1wt.eu> X-Mailer: git-send-email 2.8.0.rc2.1.gbe9624a In-Reply-To: <1486322541-8206-1-git-send-email-w@1wt.eu> References: <1486322541-8206-1-git-send-email-w@1wt.eu> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Return-Path: From: Jann Horn commit dd111be69114cc867f8e826284559bfbc1c40e37 upstream. When root activates a swap partition whose header has the wrong endianness, nr_badpages elements of badpages are swabbed before nr_badpages has been checked, leading to a buffer overrun of up to 8GB. This normally is not a security issue because it can only be exploited by root (more specifically, a process with CAP_SYS_ADMIN or the ability to modify a swap file/partition), and such a process can already e.g. modify swapped-out memory of any other userspace process on the system. Link: http://lkml.kernel.org/r/1477949533-2509-1-git-send-email-jann@thejh.net Signed-off-by: Jann Horn Acked-by: Kees Cook Acked-by: Jerome Marchand Acked-by: Johannes Weiner Cc: "Kirill A. Shutemov" Cc: Vlastimil Babka Cc: Hugh Dickins Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Willy Tarreau --- mm/swapfile.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/mm/swapfile.c b/mm/swapfile.c index 746af55b..d0a8983 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -1922,6 +1922,8 @@ static unsigned long read_swap_header(struct swap_info_struct *p, swab32s(&swap_header->info.version); swab32s(&swap_header->info.last_page); swab32s(&swap_header->info.nr_badpages); + if (swap_header->info.nr_badpages > MAX_SWAP_BADPAGES) + return 0; for (i = 0; i < swap_header->info.nr_badpages; i++) swab32s(&swap_header->info.badpages[i]); } -- 2.8.0.rc2.1.gbe9624a