diff mbox series

[RFC] usb: gadget: ncm: Handle decoding of multiple NTB's in unwrap call

Message ID 20230914182922.27157-1-quic_kriskura@quicinc.com
State Superseded
Headers show
Series [RFC] usb: gadget: ncm: Handle decoding of multiple NTB's in unwrap call | expand

Commit Message

Krishna Kurapati Sept. 14, 2023, 6:29 p.m. UTC 
When NCM is used with hosts like Windows PC, it is observed that there are
multiple NTB's contained in one usb request giveback. Since the driver
unwraps the obtained request data assuming only one NTB is present, we loose
the subsequent NTB's present resulting in data loss.

Fix this by checking the parsed block length with the obtained data length
in usb request and continue parsing after the last byte of current NTB.

Signed-off-by: Krishna Kurapati <quic_kriskura@quicinc.com>
---
 drivers/usb/gadget/function/f_ncm.c | 26 +++++++++++++++++++-------
 1 file changed, 19 insertions(+), 7 deletions(-)

Comments

Maciej Żenczykowski Sept. 15, 2023, 1:24 a.m. UTC | #1 
Reviewed-by: Maciej Żenczykowski <maze@google.com>

The casts should probably use the actual correct ptr type instead of void*

Feels like this should go to stable@
Krishna Kurapati Sept. 15, 2023, 2:46 a.m. UTC | #2 
On 9/15/2023 6:54 AM, Maciej Żenczykowski wrote:
> Reviewed-by: Maciej Żenczykowski <maze@google.com>
> 
> The casts should probably use the actual correct ptr type instead of void*
> 

Hi Maciej Żenczykowski,

Thanks for the review.

I initially tried to typecast it to char* since the skb->data is of that 
type. But nothing was working. So I kept it void* since the initial 
variable tmp too was kept to void*

Will add the stable and review tag as well and send v2 to be merged.

Regards,
Krishna,
diff mbox series

Patch

diff --git a/drivers/usb/gadget/function/f_ncm.c b/drivers/usb/gadget/function/f_ncm.c
index feccf4c8cc4f..f00f051438ec 100644
--- a/drivers/usb/gadget/function/f_ncm.c
+++ b/drivers/usb/gadget/function/f_ncm.c
@@ -1156,7 +1156,8 @@  static int ncm_unwrap_ntb(struct gether *port,
 			  struct sk_buff_head *list)
 {
 	struct f_ncm	*ncm = func_to_ncm(&port->func);
-	__le16		*tmp = (void *) skb->data;
+	unsigned char	*ntb_ptr = (void *) skb->data;
+	__le16		*tmp;
 	unsigned	index, index2;
 	int		ndp_index;
 	unsigned	dg_len, dg_len2;
@@ -1169,6 +1170,10 @@  static int ncm_unwrap_ntb(struct gether *port,
 	const struct ndp_parser_opts *opts = ncm->parser_opts;
 	unsigned	crc_len = ncm->is_crc ? sizeof(uint32_t) : 0;
 	int		dgram_counter;
+	int		to_process = skb->len;
+
+parse_ntb:
+	tmp = (void *) ntb_ptr;
 
 	/* dwSignature */
 	if (get_unaligned_le32(tmp) != opts->nth_sign) {
@@ -1215,7 +1220,7 @@  static int ncm_unwrap_ntb(struct gether *port,
 		 * walk through NDP
 		 * dwSignature
 		 */
-		tmp = (void *)(skb->data + ndp_index);
+		tmp = (void *)(ntb_ptr + ndp_index);
 		if (get_unaligned_le32(tmp) != ncm->ndp_sign) {
 			INFO(port->func.config->cdev, "Wrong NDP SIGN\n");
 			goto err;
@@ -1272,11 +1277,11 @@  static int ncm_unwrap_ntb(struct gether *port,
 			if (ncm->is_crc) {
 				uint32_t crc, crc2;
 
-				crc = get_unaligned_le32(skb->data +
+				crc = get_unaligned_le32(ntb_ptr +
 							 index + dg_len -
 							 crc_len);
 				crc2 = ~crc32_le(~0,
-						 skb->data + index,
+						 ntb_ptr + index,
 						 dg_len - crc_len);
 				if (crc != crc2) {
 					INFO(port->func.config->cdev,
@@ -1303,7 +1308,7 @@  static int ncm_unwrap_ntb(struct gether *port,
 							 dg_len - crc_len);
 			if (skb2 == NULL)
 				goto err;
-			skb_put_data(skb2, skb->data + index,
+			skb_put_data(skb2, ntb_ptr + index,
 				     dg_len - crc_len);
 
 			skb_queue_tail(list, skb2);
@@ -1316,10 +1321,17 @@  static int ncm_unwrap_ntb(struct gether *port,
 		} while (ndp_len > 2 * (opts->dgram_item_len * 2));
 	} while (ndp_index);
 
-	dev_consume_skb_any(skb);
-
 	VDBG(port->func.config->cdev,
 	     "Parsed NTB with %d frames\n", dgram_counter);
+
+	to_process -= block_len;
+	if (to_process != 0) {
+		ntb_ptr = (unsigned char *) (ntb_ptr + block_len);
+		goto parse_ntb;
+	}
+
+	dev_consume_skb_any(skb);
+
 	return 0;
 err:
 	skb_queue_purge(list);