From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759939AbbJIAVA (ORCPT ); Thu, 8 Oct 2015 20:21:00 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:35497 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758995AbbJIARd (ORCPT ); Thu, 8 Oct 2015 20:17:33 -0400 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "NeilBrown" , "Benjamin Randazzo" Date: Fri, 09 Oct 2015 01:12:28 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.2 089/107] md: use kzalloc() when bitmap is disabled In-Reply-To: X-SA-Exim-Connect-IP: 192.168.4.247 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.2.72-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Benjamin Randazzo commit b6878d9e03043695dbf3fa1caa6dfc09db225b16 upstream. In drivers/md/md.c get_bitmap_file() uses kmalloc() for creating a mdu_bitmap_file_t called "file". 5769 file = kmalloc(sizeof(*file), GFP_NOIO); 5770 if (!file) 5771 return -ENOMEM; This structure is copied to user space at the end of the function. 5786 if (err == 0 && 5787 copy_to_user(arg, file, sizeof(*file))) 5788 err = -EFAULT But if bitmap is disabled only the first byte of "file" is initialized with zero, so it's possible to read some bytes (up to 4095) of kernel space memory from user space. This is an information leak. 5775 /* bitmap disabled, zero the first byte and copy out */ 5776 if (!mddev->bitmap_info.file) 5777 file->pathname[0] = '\0'; Signed-off-by: Benjamin Randazzo Signed-off-by: NeilBrown [bwh: Backported to 3.2: patch both possible allocation calls] Signed-off-by: Ben Hutchings --- --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -5384,9 +5384,9 @@ static int get_bitmap_file(struct mddev int err = -ENOMEM; if (md_allow_write(mddev)) - file = kmalloc(sizeof(*file), GFP_NOIO); + file = kzalloc(sizeof(*file), GFP_NOIO); else - file = kmalloc(sizeof(*file), GFP_KERNEL); + file = kzalloc(sizeof(*file), GFP_KERNEL); if (!file) goto out;