Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753262Ab3GXOOQ (ORCPT ); Wed, 24 Jul 2013 10:14:16 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:45862 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752380Ab3GXOGv (ORCPT ); Wed, 24 Jul 2013 10:06:51 -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, "Linus Torvalds" , "Jens Axboe" , "Jonathan Salwan" , "Dan Carpenter" Date: Wed, 24 Jul 2013 15:02:45 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [81/85] drivers/cdrom/cdrom.c: use kzalloc() for failing hardware In-Reply-To: X-SA-Exim-Connect-IP: 192.168.4.101 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 Content-Length: 1861 Lines: 53 3.2.49-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Jonathan Salwan commit 542db01579fbb7ea7d1f7bb9ddcef1559df660b2 upstream. In drivers/cdrom/cdrom.c mmc_ioctl_cdrom_read_data() allocates a memory area with kmalloc in line 2885. 2885 cgc->buffer = kmalloc(blocksize, GFP_KERNEL); 2886 if (cgc->buffer == NULL) 2887 return -ENOMEM; In line 2908 we can find the copy_to_user function: 2908 if (!ret && copy_to_user(arg, cgc->buffer, blocksize)) The cgc->buffer is never cleaned and initialized before this function. If ret = 0 with the previous basic block, it's possible to display some memory bytes in kernel space from userspace. When we read a block from the disk it normally fills the ->buffer but if the drive is malfunctioning there is a chance that it would only be partially filled. The result is an leak information to userspace. Signed-off-by: Dan Carpenter Cc: Jens Axboe Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Ben Hutchings --- drivers/cdrom/cdrom.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/drivers/cdrom/cdrom.c +++ b/drivers/cdrom/cdrom.c @@ -2885,7 +2885,7 @@ static noinline int mmc_ioctl_cdrom_read if (lba < 0) return -EINVAL; - cgc->buffer = kmalloc(blocksize, GFP_KERNEL); + cgc->buffer = kzalloc(blocksize, GFP_KERNEL); if (cgc->buffer == NULL) return -ENOMEM; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/