USB: gadget: bRequestType is a bitfield, not a enum

mainline inclusion
from mainline-v5.16-rc6
commit f08adf5a
category: bugfix
bugzilla: NA
CVE: CVE-2021-39685

--------------------------------

Szymon rightly pointed out that the previous check for the endpoint
direction in bRequestType was not looking at only the bit involved, but
rather the whole value.  Normally this is ok, but for some request
types, bits other than bit 8 could be set and the check for the endpoint
length could not stall correctly.

Fix that up by only checking the single bit.

Fixes: 153a2d7e ("USB: gadget: detect too-big endpoint 0 requests")
Cc: Felipe Balbi <balbi@kernel.org>
Reported-by: NSzymon Heidrich <szymon.heidrich@gmail.com>
Link: https://lore.kernel.org/r/20211214184621.385828-1-gregkh@linuxfoundation.orgSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>
Reviewed-by: NXiu Jianfeng <xiujianfeng@huawei.com>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>

drivers/usb/gadget/composite.c

@@ -1570,14 +1570,14 @@ composite_setup(struct usb_gadget *gadget, const struct usb_ctrlrequest *ctrl)
 	u8				endp;
 
 	if (w_length > USB_COMP_EP0_BUFSIZ) {
-		if (ctrl->bRequestType == USB_DIR_OUT) {
-			goto done;
-		} else {
+		if (ctrl->bRequestType & USB_DIR_IN) {
 			/* Cast away the const, we are going to overwrite on purpose. */
 			__le16 *temp = (__le16 *)&ctrl->wLength;
 
 			*temp = cpu_to_le16(USB_COMP_EP0_BUFSIZ);
 			w_length = USB_COMP_EP0_BUFSIZ;
+		} else {
+			goto done;
 		}
 	}
 

drivers/usb/gadget/legacy/dbgp.c

@@ -346,14 +346,14 @@ static int dbgp_setup(struct usb_gadget *gadget,
 	u16 len = 0;
 
 	if (length > DBGP_REQ_LEN) {
-		if (ctrl->bRequestType == USB_DIR_OUT) {
-			return err;
-		} else {
+		if (ctrl->bRequestType & USB_DIR_IN) {
 			/* Cast away the const, we are going to overwrite on purpose. */
 			__le16 *temp = (__le16 *)&ctrl->wLength;
 
 			*temp = cpu_to_le16(DBGP_REQ_LEN);
 			length = DBGP_REQ_LEN;
+		} else {
+			return err;
 		}
 	}
 

drivers/usb/gadget/legacy/inode.c

@@ -1335,14 +1335,14 @@ gadgetfs_setup (struct usb_gadget *gadget, const struct usb_ctrlrequest *ctrl)
 	u16				w_length = le16_to_cpu(ctrl->wLength);
 
 	if (w_length > RBUF_SIZE) {
-		if (ctrl->bRequestType == USB_DIR_OUT) {
-			return value;
-		} else {
+		if (ctrl->bRequestType & USB_DIR_IN) {
 			/* Cast away the const, we are going to overwrite on purpose. */
 			__le16 *temp = (__le16 *)&ctrl->wLength;
 
 			*temp = cpu_to_le16(RBUF_SIZE);
 			w_length = RBUF_SIZE;
+		} else {
+			return value;
 		}
 	}