A second regression was found in the immediate data transfer (IDT) support which was added to 5.2 kernel

IDT is used to transfer small amounts of data (up to 8 bytes) in the field normally used for data dma address, thus avoiding dma mapping.

If the data was not already dma mapped, then IDT support assumed data was in urb->transfer_buffer, and did not take into accound that even small amounts of data (8 bytes) can be in a scatterlist instead.

This caused a NULL pointer dereference when sg_dma_len() was used with non-dma mapped data.

Solve this by not using IDT if scatter gather buffer list is used.

Fixes: 33e39350ebd2 ("usb: xhci: add Immediate Data Transfer support") Cc: stable@vger.kernel.org # v5.2 Reported-by: Maik Stohn maik.stohn@seal-one.com Tested-by: Maik Stohn maik.stohn@seal-one.com CC: Nicolas Saenz Julienne nsaenzjulienne@suse.de Signed-off-by: Mathias Nyman mathias.nyman@linux.intel.com --- drivers/usb/host/xhci.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/host/xhci.h b/drivers/usb/host/xhci.h index 7a26496..f5c4144 100644 --- a/drivers/usb/host/xhci.h +++ b/drivers/usb/host/xhci.h @@ -2175,7 +2175,8 @@ static inline bool xhci_urb_suitable_for_idt(struct urb *urb) if (!usb_endpoint_xfer_isoc(&urb->ep->desc) && usb_urb_dir_out(urb) && usb_endpoint_maxp(&urb->ep->desc) >= TRB_IDT_MAX_SIZE && urb->transfer_buffer_length <= TRB_IDT_MAX_SIZE && - !(urb->transfer_flags & URB_NO_TRANSFER_DMA_MAP)) + !(urb->transfer_flags & URB_NO_TRANSFER_DMA_MAP) && + !urb->num_sgs) return true;

return false;