USB: serial: keyspan: fix NULL-derefs on open() and write()

PATCH In review Johan Hovold 2 participants 2 messages Oct 3, 2019 – Oct 4, 2019

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Stable branch USB USB serial

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Johan Hovold

author maintainer

2019-10-03 13:50 UTC #0 lore raw

PATCH 1/1 USB: serial: keyspan: fix NULL-derefs on open() and write()

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 <[email protected]> # 2.6.21

Signed-off-by Johan Hovold <[email protected]>

---
 drivers/usb/serial/keyspan.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

drivers/usb/serial/keyspan.c +2 -2

index d34779fe4a8d..e66a59ef43a1 100644
@@ -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";

Signature · 1 line

2.23.0

Greg Kroah-Hartman

maintainer Reviewed-by on v1 1/1

2019-10-04 08:54 UTC #1 lore raw

Quoted 42 lines · Johan Hovold

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

	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

Quoted 3 lines

Fixes fdcba53e2d58 ("fix for bugzilla #7544 (keyspan USB-to-serial converter)")
Cc stable <[email protected]> # 2.6.21
Signed-off-by Johan Hovold <[email protected]>

Reviewed-by Greg Kroah-Hartman <[email protected]>