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USB: serial: option: add interface-number sanity check to flag handling

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Add an interface-number sanity check before testing the device flags to
avoid relying on undefined behaviour when left shifting in case a device
uses an interface number greater than or equal to BITS_PER_LONG (i.e. 64
or 32).

Reported-by: syzbot+8881b478dad0a7971f79@syzkaller.appspotmail.com
Fixes: c3a65808f0 ("USB: serial: option: reimplement interface masking")
Cc: stable@vger.kernel.org
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Johan Hovold <johan@kernel.org>
This commit is contained in:
Johan Hovold 2020-12-09 11:42:21 +01:00
parent daa919196b
commit a251963f76
1 changed files with 21 additions and 2 deletions
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23
drivers/usb/serial/option.c
View file

@ -561,6 +561,9 @@ static void option_instat_callback(struct urb *urb);
/* Device flags */
/* Highest interface number which can be used with NCTRL() and RSVD() */
#define FLAG_IFNUM_MAX 7
/* Interface does not support modem-control requests */
#define NCTRL(ifnum) ((BIT(ifnum) & 0xff) << 8)
@ -2089,6 +2092,14 @@ static struct usb_serial_driver * const serial_drivers[] = {
module_usb_serial_driver(serial_drivers, option_ids);
static bool iface_is_reserved(unsigned long device_flags, u8 ifnum)
{
if (ifnum > FLAG_IFNUM_MAX)
return false;
return device_flags & RSVD(ifnum);
}
static int option_probe(struct usb_serial *serial,
const struct usb_device_id *id)
{
@ -2105,7 +2116,7 @@ static int option_probe(struct usb_serial *serial,
* the same class/subclass/protocol as the serial interfaces. Look at
* the Windows driver .INF files for reserved interface numbers.
*/
if (device_flags & RSVD(iface_desc->bInterfaceNumber))
if (iface_is_reserved(device_flags, iface_desc->bInterfaceNumber))
return -ENODEV;
/*
@ -2121,6 +2132,14 @@ static int option_probe(struct usb_serial *serial,
return 0;
}
static bool iface_no_modem_control(unsigned long device_flags, u8 ifnum)
{
if (ifnum > FLAG_IFNUM_MAX)
return false;
return device_flags & NCTRL(ifnum);
}
static int option_attach(struct usb_serial *serial)
{
struct usb_interface_descriptor *iface_desc;
@ -2136,7 +2155,7 @@ static int option_attach(struct usb_serial *serial)
iface_desc = &serial->interface->cur_altsetting->desc;
if (!(device_flags & NCTRL(iface_desc->bInterfaceNumber)))
if (!iface_no_modem_control(device_flags, iface_desc->bInterfaceNumber))
data->use_send_setup = 1;
if (device_flags & ZLP)