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USB: Fix descriptor count when handling invalid MBIM extended descriptor

PATCH New pip-izony 1 participant 1 message Sep 28, 2025 USB

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PATCH 1/1 USB: Fix descriptor count when handling invalid MBIM extended descriptor

From: Seungjin Bae <[email protected]>

In cdc_parse_cdc_header(), the check for the USB_CDC_MBIM_EXTENDED_TYPE descriptor was using 'break' upon detecting an invalid length.

This was incorrect because 'break' only exits the switch statement, causing the code to fall through to cnt++, thus incorrectly incrementing the count of parsed descriptors for a descriptor that was actually invalid and being discarded.

This patch changes 'break' to 'goto next_desc;' to ensure that the logic skips the counter increment and correctly proceeds to the next descriptor in the buffer. This maintains an accurate count of only the successfully parsed descriptors.

Fixes e4c6fb7794982 ("usbnet: move the CDC parser into USB core")
---
 drivers/usb/core/message.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
drivers/usb/core/message.c +1 -1
index d2b2787be409..6138468c67c4 100644
@@ -2431,7 +2431,7 @@ int cdc_parse_cdc_header(struct usb_cdc_parsed_header *hdr,
 			break;
 		case USB_CDC_MBIM_EXTENDED_TYPE:
 			if (elength < sizeof(struct usb_cdc_mbim_extended_desc))
-				break;
+				goto next_desc;
 			hdr->usb_cdc_mbim_extended_desc =
 				(struct usb_cdc_mbim_extended_desc *)buffer;
 			break;
Signature · 1 line
2.43.0