From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Al Viro , Karsten Keil , Kees Cook , "David S. Miller" Subject: [PATCH 4.17 36/42] isdn: Disable IIOCDBGVAR Date: Tue, 21 Aug 2018 08:21:08 +0200 Message-Id: <20180821055019.382973275@linuxfoundation.org> In-Reply-To: <20180821055017.596264829@linuxfoundation.org> References: <20180821055017.596264829@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: 4.17-stable review patch. If anyone has any objections, please let me know. ------------------ From: Kees Cook [ Upstream commit 5e22002aa8809e2efab2da95855f73f63e14a36c ] It was possible to directly leak the kernel address where the isdn_dev structure pointer was stored. This is a kernel ASLR bypass for anyone with access to the ioctl. The code had been present since the beginning of git history, though this shouldn't ever be needed for normal operation, therefore remove it. Reported-by: Al Viro Cc: Karsten Keil Signed-off-by: Kees Cook Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- drivers/isdn/i4l/isdn_common.c | 8 +------- 1 file changed, 1 insertion(+), 7 deletions(-) --- a/drivers/isdn/i4l/isdn_common.c +++ b/drivers/isdn/i4l/isdn_common.c @@ -1640,13 +1640,7 @@ isdn_ioctl(struct file *file, uint cmd, } else return -EINVAL; case IIOCDBGVAR: - if (arg) { - if (copy_to_user(argp, &dev, sizeof(ulong))) - return -EFAULT; - return 0; - } else - return -EINVAL; - break; + return -EINVAL; default: if ((cmd & IIOCDRVCTL) == IIOCDRVCTL) cmd = ((cmd >> _IOC_NRSHIFT) & _IOC_NRMASK) & ISDN_DRVIOCTL_MASK;