[PATCH 3.16 251/328] USB: usbdevfs: sanitize flags more

Ben Hutchings
2018-12-09T21:59:52Z

From: Oliver Neukum <oneukum@suse.com>

commit 7a68d9fb851012829c29e770621905529bd9490b upstream.

Requesting a ZERO_PACKET or not is sensible only for output.
In the input direction the device decides.
Likewise accepting short packets makes sense only for input.

This allows operation with panic_on_warn without opening up
a local DOS.

Signed-off-by: Oliver Neukum <oneukum@suse.com>
Reported-by: syzbot+843efa30c8821bd69f53@syzkaller.appspotmail.com
Fixes: 0cb54a3e47cb ("USB: debugging code shouldn't alter control flow")
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
drivers/usb/core/devio.c | 19 ++++++++++++++++---
1 file changed, 16 insertions(+), 3 deletions(-)

--- a/drivers/usb/core/devio.c
+++ b/drivers/usb/core/devio.c
@@ -1291,10 +1291,13 @@ static int proc_do_submiturb(struct usb_
struct async *as = NULL;
struct usb_ctrlrequest *dr = NULL;
unsigned int u, totlen, isofrmlen;
- int i, ret, is_in, num_sgs = 0, ifnum = -1;
+ int i, ret, num_sgs = 0, ifnum = -1;
int number_of_packets = 0;
unsigned int stream_id = 0;
void *buf;
+ bool is_in;
+ bool allow_short = false;
+ bool allow_zero = false;
unsigned long mask = USBDEVFS_URB_SHORT_NOT_OK |
USBDEVFS_URB_BULK_CONTINUATION |
USBDEVFS_URB_NO_FSBR |
@@ -1326,6 +1329,8 @@ static int proc_do_submiturb(struct usb_
u = 0;
switch(uurb->type) {
case USBDEVFS_URB_TYPE_CONTROL:
+ if (is_in)
+ allow_short = true;
if (!usb_endpoint_xfer_control(&ep->desc))
return -EINVAL;
/* min 8 byte setup packet */
@@ -1366,6 +1371,10 @@ static int proc_do_submiturb(struct usb_
break;

case USBDEVFS_URB_TYPE_BULK:
+ if (!is_in)
+ allow_zero = true;
+ else
+ allow_short = true;
switch (usb_endpoint_type(&ep->desc)) {
case USB_ENDPOINT_XFER_CONTROL:
case USB_ENDPOINT_XFER_ISOC:
@@ -1386,6 +1395,10 @@ static int proc_do_submiturb(struct usb_
if (!usb_endpoint_xfer_int(&ep->desc))
return -EINVAL;
interrupt_urb:
+ if (!is_in)
+ allow_zero = true;
+ else
+ allow_short = true;
break;

case USBDEVFS_URB_TYPE_ISO:
@@ -1515,11 +1528,11 @@ static int proc_do_submiturb(struct usb_
u = (is_in ? URB_DIR_IN : URB_DIR_OUT);
if (uurb->flags & USBDEVFS_URB_ISO_ASAP)
u |= URB_ISO_ASAP;
- if (uurb->flags & USBDEVFS_URB_SHORT_NOT_OK && is_in)
+ if (allow_short && uurb->flags & USBDEVFS_URB_SHORT_NOT_OK)
u |= URB_SHORT_NOT_OK;
if (uurb->flags & USBDEVFS_URB_NO_FSBR)
u |= URB_NO_FSBR;
- if (uurb->flags & USBDEVFS_URB_ZERO_PACKET)
+ if (allow_zero && uurb->flags & USBDEVFS_URB_ZERO_PACKET)
u |= URB_ZERO_PACKET;
if (uurb->flags & USBDEVFS_URB_NO_INTERRUPT)
u |= URB_NO_INTERRUPT;