A type of inconsistency that can show up in control URBs is when the
setup packet's wLength value does not match the URB's
transfer_buffer_length field. The two should always be equal;
differences could lead to information leaks or undefined behavior for
OUT transfers or overruns for IN transfers.
This patch adds a test for such mismatches during URB submission. If
the test fails, the submission is rejected with a -EBADR error code
(which is not used elsewhere in the USB core), and a debugging message
is logged for people interested in tracking down these errors.
Signed-off-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
CC: Johan Hovold <johan@xxxxxxxxxx>
---
[as1961]
Documentation/driver-api/usb/error-codes.rst | 3 +++
drivers/usb/core/urb.c | 6 ++++++
2 files changed, 9 insertions(+)
Index: usb-devel/drivers/usb/core/urb.c
===================================================================
--- usb-devel.orig/drivers/usb/core/urb.c
+++ usb-devel/drivers/usb/core/urb.c
@@ -410,6 +410,12 @@ int usb_submit_urb(struct urb *urb, gfp_
dev_WARN_ONCE(&dev->dev, (usb_pipeout(urb->pipe) != is_out),
"BOGUS control dir, pipe %x doesn't match bRequestType %x\n",
urb->pipe, setup->bRequestType);
+ if (le16_to_cpu(setup->wLength) != urb->transfer_buffer_length) {
+ dev_dbg(&dev->dev, "BOGUS control len %d doesn't match transfer length %d\n",
+ le16_to_cpu(setup->wLength),
+ urb->transfer_buffer_length);
+ return -EBADR;
+ }
} else {
is_out = usb_endpoint_dir_out(&ep->desc);
}
Index: usb-devel/Documentation/driver-api/usb/error-codes.rst
===================================================================
--- usb-devel.orig/Documentation/driver-api/usb/error-codes.rst
+++ usb-devel/Documentation/driver-api/usb/error-codes.rst
@@ -61,6 +61,9 @@ USB-specific:
(c) requested data transfer length is invalid: negative
or too large for the host controller.
+``-EBADR`` The wLength value in a control URB's setup packet does
+ not match the URB's transfer_buffer_length.
+
``-ENOSPC`` This request would overcommit the usb bandwidth reserved
for periodic transfers (interrupt, isochronous).
