Fix NULL-pointer dereferences on open() and write() which can be triggered by a malicious USB device.

The current URB allocation helper would fail to initialise the newly allocated URB if the device has unexpected endpoint descriptors, something which could lead NULL-pointer dereferences in a number of open() and write() paths when accessing the URB. For example:

BUG: kernel NULL pointer dereference, address: 0000000000000000 ... RIP: 0010:usb_clear_halt+0x11/0xc0 ... Call Trace: ? tty_port_open+0x4d/0xd0 keyspan_open+0x70/0x160 [keyspan] serial_port_activate+0x5b/0x80 [usbserial] tty_port_open+0x7b/0xd0 ? check_tty_count+0x43/0xa0 tty_open+0xf1/0x490

BUG: kernel NULL pointer dereference, address: 0000000000000000 ... RIP: 0010:keyspan_write+0x14e/0x1f3 [keyspan] ... Call Trace: serial_write+0x43/0xa0 [usbserial] n_tty_write+0x1af/0x4f0 ? do_wait_intr_irq+0x80/0x80 ? process_echoes+0x60/0x60 tty_write+0x13f/0x2f0

BUG: kernel NULL pointer dereference, address: 0000000000000000 ... RIP: 0010:keyspan_usa26_send_setup+0x298/0x305 [keyspan] ... Call Trace: keyspan_open+0x10f/0x160 [keyspan] serial_port_activate+0x5b/0x80 [usbserial] tty_port_open+0x7b/0xd0 ? check_tty_count+0x43/0xa0 tty_open+0xf1/0x490

Fixes: fdcba53e2d58 ("fix for bugzilla #7544 (keyspan USB-to-serial converter)") Cc: stable stable@vger.kernel.org # 2.6.21 Signed-off-by: Johan Hovold johan@kernel.org --- drivers/usb/serial/keyspan.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/serial/keyspan.c b/drivers/usb/serial/keyspan.c index d34779fe4a8d..e66a59ef43a1 100644 --- a/drivers/usb/serial/keyspan.c +++ b/drivers/usb/serial/keyspan.c @@ -1741,8 +1741,8 @@ static struct urb *keyspan_setup_urb(struct usb_serial *serial, int endpoint,

ep_desc = find_ep(serial, endpoint); if (!ep_desc) { - /* leak the urb, something's wrong and the callers don't care */ - return urb; + usb_free_urb(urb); + return NULL; } if (usb_endpoint_xfer_int(ep_desc)) { ep_type_name = "INT";