ioctl: Allow ZLP control writes

Closes mcuee#21 Signed-off-by: Tormod Volden <[email protected]>
tormodvolden · Oct 13, 2021 · 9acdc23 · 9acdc23
1 parent ee27cd5
commit 9acdc23
Showing 1 changed file with 3 additions and 2 deletions.
diff --git a/libusb/src/driver/ioctl.c b/libusb/src/driver/ioctl.c
@@ -668,8 +668,9 @@ NULL : input_buffer + sizeof(libusb_request),
 
 		dispCtlCode = "CONTROL_WRITE";
 
-		// check if the request and buffer is valid
-		if (!request || !transfer_buffer_mdl || input_buffer_length < sizeof(libusb_request))
+		/* we don't check 'transfer_buffer_mdl' here because it might be NULL */
+		/* if the DLL requests to send a zero-length control packet */
+		if (!request || input_buffer_length < sizeof(libusb_request))
 		{
 			USBERR("%s: invalid transfer request\n", dispCtlCode);
 			status = STATUS_INVALID_PARAMETER;