USB: ehci: paranoia, reject large control transfers

Some EHCI fault paths with large control transfers aren't coded.  Avoid
problems by rejecting transfers that may need two qTDs (16+ KB).  This is
mostly paranoia; even 4 KB transfers are rare, and most HCDs use lower
limits (so it's unlikely anyone would ever try such a thing).

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 8 insertions, 2 deletions

diff --git a/drivers/usb/host/ehci-hcd.c b/drivers/usb/host/ehci-hcd.c
index 8c3e860bfce3..a02dcff5eb21 100644
--- a/drivers/usb/host/ehci-hcd.c
+++ b/drivers/usb/host/ehci-hcd.c
@@ -764,8 +764,14 @@ static int ehci_urb_enqueue (
         INIT_LIST_HEAD (&qtd_list);
 
         switch (usb_pipetype (urb->pipe)) {
-        // case PIPE_CONTROL:
-        // case PIPE_BULK:
+        case PIPE_CONTROL:
+                /* qh_completions() code doesn't handle all the fault cases
+                 * in multi-TD control transfers.  Even 1KB is rare anyway.
+                 */
+                if (urb->transfer_buffer_length > (16 * 1024))
+                        return -EMSGSIZE;
+                /* FALLTHROUGH */
+        /* case PIPE_BULK: */
         default:
                 if (!qh_urb_transaction (ehci, urb, &qtd_list, mem_flags))
                         return -ENOMEM;