[PATCH] usb: gadget: f_ncm: Use unsigned int for ndp_index

[PATCH] usb: gadget: f_ncm: Use unsigned int for ndp_index

[Sonali Pradhan]

The variable ndp_index is declared as a signed integer, but it stores
the return value of get_ncm(), which is unsigned.

A malicious host can supply a large offset that overflows the signed
ndp_index, making it negative. Because ndp_index is compared against
unsigned bounds, this negative value bypasses sanity checks and leads
to an out-of-bounds read when calculating the address of the NDP
block (ntb_ptr + ndp_index).

Fix this by changing ndp_index to unsigned int to ensure consistent
unsigned comparisons throughout the function.

Fixes: 370af734dfaf ("usb: gadget: NCM: RX function support multiple NDPs")
Cc: stable@vger.kernel.org
Signed-off-by: Sonali Pradhan <sonalipradhan@google.com>
---
 drivers/usb/gadget/function/f_ncm.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/usb/gadget/function/f_ncm.c b/drivers/usb/gadget/function/f_ncm.c
index 64eabda2f546..bf02545b37a2 100644
--- a/drivers/usb/gadget/function/f_ncm.c
+++ b/drivers/usb/gadget/function/f_ncm.c
@@ -1171,7 +1171,7 @@ static int ncm_unwrap_ntb(struct gether *port,
 	unsigned char	*ntb_ptr = skb->data;
 	__le16		*tmp;
 	unsigned	index, index2;
-	int		ndp_index;
+	unsigned int	ndp_index;
 	unsigned	dg_len, dg_len2;
 	unsigned	ndp_len;
 	unsigned	block_len;
-- 
2.55.0.229.g6434b31f56-goog