ACK: [Trusty SRU] Fix for CVE-2017-16911

[Colin Ian King]

On 18/07/18 14:35, Stefan Bader wrote:
> From d9048d4e4a99354071874d7df13300275a0e2884 Mon Sep 17 00:00:00 2001
> From: Shuah Khan <shuahkh at osg.samsung.com>
> Date: Thu, 7 Dec 2017 14:16:49 -0700
> Subject: [PATCH] usbip: prevent vhci_hcd driver from leaking a socket pointer
>  address
> 
> When a client has a USB device attached over IP, the vhci_hcd driver is
> locally leaking a socket pointer address via the
> 
> /sys/devices/platform/vhci_hcd/status file (world-readable) and in debug
> output when "usbip --debug port" is run.
> 
> Fix it to not leak. The socket pointer address is not used at the moment
> and it was made visible as a convenient way to find IP address from socket
> pointer address by looking up /proc/net/{tcp,tcp6}.
> 
> As this opens a security hole, the fix replaces socket pointer address with
> sockfd.
> 
> Reported-by: Secunia Research <vuln at secunia.com>
> Cc: stable <stable at vger.kernel.org>
> Signed-off-by: Shuah Khan <shuahkh at osg.samsung.com>
> Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
> 
> CVE-2017-16911
> 
> (backported from commit 2f2d0088eb93db5c649d2a5e34a3800a8a935fc5)
> [smb: driver still in staging, adapted to different output format]
> Signed-off-by: Stefan Bader <stefan.bader at canonical.com>
> ---
> 
> The driver is in staging still and also used a different output format.
> I believe this should cover the original approach and is compile tested
> on x86_64.
> 
> -Stefan
> 
>  drivers/staging/usbip/usbip_common.h               |  1 +
>  .../staging/usbip/userspace/libsrc/vhci_driver.c   |  8 ++++----
>  drivers/staging/usbip/vhci_sysfs.c                 | 22 ++++++++++++++--------
>  3 files changed, 19 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/staging/usbip/usbip_common.h b/drivers/staging/usbip/usbip_common.h
> index 7e6c543..3eb8038 100644
> --- a/drivers/staging/usbip/usbip_common.h
> +++ b/drivers/staging/usbip/usbip_common.h
> @@ -276,6 +276,7 @@ struct usbip_device {
>  	/* lock for status */
>  	spinlock_t lock;
>  
> +	int sockfd;
>  	struct socket *tcp_socket;
>  
>  	struct task_struct *tcp_rx;
> diff --git a/drivers/staging/usbip/userspace/libsrc/vhci_driver.c b/drivers/staging/usbip/userspace/libsrc/vhci_driver.c
> index 1091bb2..f86d3c8 100644
> --- a/drivers/staging/usbip/userspace/libsrc/vhci_driver.c
> +++ b/drivers/staging/usbip/userspace/libsrc/vhci_driver.c
> @@ -69,12 +69,12 @@ static int parse_status(char *value)
>  
>  	while (*c != '\0') {
>  		int port, status, speed, devid;
> -		unsigned long socket;
> +		int sockfd;
>  		char lbusid[SYSFS_BUS_ID_SIZE];
>  
> -		ret = sscanf(c, "%d %d %d %x %lx %s\n",
> +		ret = sscanf(c, "%d %d %d %x %u %s\n",
>  				&port, &status, &speed,
> -				&devid, &socket, lbusid);
> +				&devid, &sockfd, lbusid);
>  
>  		if (ret < 5) {
>  			dbg("sscanf failed: %d", ret);
> @@ -83,7 +83,7 @@ static int parse_status(char *value)
>  
>  		dbg("port %d status %d speed %d devid %x",
>  				port, status, speed, devid);
> -		dbg("socket %lx lbusid %s", socket, lbusid);
> +		dbg("sockfd %u lbusid %s", sockfd, lbusid);
>  
>  
>  		/* if a device is connected, look at it */
> diff --git a/drivers/staging/usbip/vhci_sysfs.c b/drivers/staging/usbip/vhci_sysfs.c
> index 9b51586..db057c3 100644
> --- a/drivers/staging/usbip/vhci_sysfs.c
> +++ b/drivers/staging/usbip/vhci_sysfs.c
> @@ -39,15 +39,20 @@ static ssize_t status_show(struct device *dev, struct device_attribute *attr,
>  
>  	/*
>  	 * output example:
> -	 * prt sta spd dev socket           local_busid
> -	 * 000 004 000 000         c5a7bb80 1-2.3
> -	 * 001 004 000 000         d8cee980 2-3.4
> +	 * prt sta spd dev sockfd    local_busid
> +	 * 000 004 000 000 3         1-2.3
> +	 * 001 004 000 000 4         2-3.4
> +	 *
> +	 * Output includes socket fd instead of socket pointer address to avoid
> +	 * leaking kernel memory address in:
> +	 *     /sys/devices/platform/vhci_hcd.0/status and in debug output.
> +	 * The socket pointer address is not used at the moment and it was made
> +	 * visible as a convenient way to find IP address from socket pointer
> +	 * address by looking up /proc/net/{tcp,tcp6}. As this opens a security
> +	 * hole, the change is made to use sockfd instead.
>  	 *
> -	 * IP address can be retrieved from a socket pointer address by looking
> -	 * up /proc/net/{tcp,tcp6}. Also, a userland program may remember a
> -	 * port number and its peer IP address.
>  	 */
> -	out += sprintf(out, "prt sta spd bus dev socket           "
> +	out += sprintf(out, "prt sta spd bus dev sockfd    "
>  		       "local_busid\n");
>  
>  	for (i = 0; i < VHCI_NPORTS; i++) {
> @@ -59,7 +64,7 @@ static ssize_t status_show(struct device *dev, struct device_attribute *attr,
>  		if (vdev->ud.status == VDEV_ST_USED) {
>  			out += sprintf(out, "%03u %08x ",
>  				       vdev->speed, vdev->devid);
> -			out += sprintf(out, "%16p ", vdev->ud.tcp_socket);
> +			out += sprintf(out, "%9u ", vdev->ud.sockfd);
>  			out += sprintf(out, "%s", dev_name(&vdev->udev->dev));
>  
>  		} else {
> @@ -219,6 +224,7 @@ static ssize_t store_attach(struct device *dev, struct device_attribute *attr,
>  
>  	vdev->devid         = devid;
>  	vdev->speed         = speed;
> +	vdev->ud.sockfd     = sockfd;
>  	vdev->ud.tcp_socket = socket;
>  	vdev->ud.status     = VDEV_ST_NOTASSIGNED;
>  
> 

Looks good.

Acked-by: Colin Ian King <colin.king at canonical.com>