Commit 7652dd2c authored by Alan Stern's avatar Alan Stern Committed by Greg Kroah-Hartman
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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: default avatarJohan Hovold <johan@kernel.org>
Signed-off-by: default avatarAlan Stern <stern@rowland.harvard.edu>
Link: https://lore.kernel.org/r/20210526153244.GA1400430@rowland.harvard.edu

Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 61a140f0
......@@ -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).
......
......@@ -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);
}
......
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