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USB: core: Check buffer length matches wLength for control transfers 

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.

Reviewed-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Link: https://lore.kernel.org/r/20210526153244.GA1400430@rowland.harvard.edu
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Alan Stern 2021-05-26 11:32:44 -04:00 committed by Greg Kroah-Hartman
parent 61a140f08e
commit 7652dd2c5c
2 changed files with 9 additions and 0 deletions
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3
Documentation/driver-api/usb/error-codes.rst
View File

@ -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).

6
drivers/usb/core/urb.c
View File

@ -410,6 +410,12 @@ int usb_submit_urb(struct urb *urb, gfp_t mem_flags)
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);
}