From 7652dd2c5cb7b656471cc801d619fe24120643a3 Mon Sep 17 00:00:00 2001 From: Alan Stern Date: Wed, 26 May 2021 11:32:44 -0400 Subject: [PATCH] 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 Signed-off-by: Alan Stern Link: https://lore.kernel.org/r/20210526153244.GA1400430@rowland.harvard.edu Signed-off-by: Greg Kroah-Hartman --- Documentation/driver-api/usb/error-codes.rst | 3 +++ drivers/usb/core/urb.c | 6 ++++++ 2 files changed, 9 insertions(+) diff --git a/Documentation/driver-api/usb/error-codes.rst b/Documentation/driver-api/usb/error-codes.rst index a3e84bfac776..8f9790c2d6f8 100644 --- a/Documentation/driver-api/usb/error-codes.rst +++ b/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). diff --git a/drivers/usb/core/urb.c b/drivers/usb/core/urb.c index 279b3921ff8f..30727729a44c 100644 --- a/drivers/usb/core/urb.c +++ b/drivers/usb/core/urb.c @@ -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); }