Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030311AbVIOBFj (ORCPT ); Wed, 14 Sep 2005 21:05:39 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1030309AbVIOBFd (ORCPT ); Wed, 14 Sep 2005 21:05:33 -0400 Received: from smtp.osdl.org ([65.172.181.4]:39361 "EHLO smtp.osdl.org") by vger.kernel.org with ESMTP id S1030311AbVIOBFF (ORCPT ); Wed, 14 Sep 2005 21:05:05 -0400 Message-Id: <20050915010400.221519000@localhost.localdomain> References: <20050915010343.577985000@localhost.localdomain> Date: Wed, 14 Sep 2005 18:03:44 -0700 From: Chris Wright To: linux-kernel@vger.kernel.org, stable@kernel.org, Kirill Korotaev Cc: Justin Forbes , Zwane Mwaikambo , "Theodore Ts'o" , Randy Dunlap , Chuck Wolber , torvalds@osdl.org, akpm@osdl.org, alan@lxorguk.ukuu.org.uk, Chris Wright , Maxim Giryaev Subject: [PATCH 01/11] [PATCH] lost fput in 32bit ioctl on x86-64 Content-Disposition: inline; filename=lost-fput-in-32bit-ioctl-on-x86-64.patch Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2117 Lines: 65 -stable review patch. If anyone has any objections, please let us know. ------------------ This patch adds lost fput in 32bit tiocgdev ioctl on x86-64 I believe this is a security issues, since user can fget() file as many times as he wants to. So file refcounter can be overlapped and first fput() will free resources though there will be still structures pointing to the file, mnt, dentry etc. Also fput() sets f_dentry and f_vfsmnt to NULL, so other file users will OOPS. The oops can be done under files_lock and others, so this is really exploitable DoS on SMP. Didn't checked it on practice actually. (chrisw: Update to use fget_light/fput_light) Signed-Off-By: Kirill Korotaev Signed-Off-By: Maxim Giryaev Signed-off-by: Chris Wright --- arch/x86_64/ia32/ia32_ioctl.c | 17 +++++++++++++---- 1 files changed, 13 insertions(+), 4 deletions(-) Index: linux-2.6.13.y/arch/x86_64/ia32/ia32_ioctl.c =================================================================== --- linux-2.6.13.y.orig/arch/x86_64/ia32/ia32_ioctl.c +++ linux-2.6.13.y/arch/x86_64/ia32/ia32_ioctl.c @@ -24,17 +24,26 @@ static int tiocgdev(unsigned fd, unsigned cmd, unsigned int __user *ptr) { - struct file *file = fget(fd); + struct file *file; struct tty_struct *real_tty; + int fput_needed, ret; + file = fget_light(fd, &fput_needed); if (!file) return -EBADF; + + ret = -EINVAL; if (file->f_op->ioctl != tty_ioctl) - return -EINVAL; + goto out; real_tty = (struct tty_struct *)file->private_data; if (!real_tty) - return -EINVAL; - return put_user(new_encode_dev(tty_devnum(real_tty)), ptr); + goto out; + + ret = put_user(new_encode_dev(tty_devnum(real_tty)), ptr); + +out: + fput_light(file, fput_needed); + return ret; } #define RTC_IRQP_READ32 _IOR('p', 0x0b, unsigned int) /* Read IRQ rate */ -- - 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/