[PATCH net-next v3 02/12] net: mctp: usb: Use packet-length max for maximum packet-size check
From: Jeremy Kerr <jk@codeconstruct.com.au>
Date: 2026-07-08 09:59:00
Also in:
linux-usb
Subsystem:
management component transport protocol (mctp), networking drivers, the rest, usb subsystem · Maintainers:
Jeremy Kerr, Matt Johnston, Andrew Lunn, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds, Greg Kroah-Hartman
The max packet size is smaller than the max transfer size, as we only have a u8 length field in the transport header. Add a define for the maximum representable length, and use that for our check. Use this for the MTU maximum calculation too. Signed-off-by: Jeremy Kerr <jk@codeconstruct.com.au> --- drivers/net/mctp/mctp-usb.c | 2 +- include/linux/usb/mctp-usb.h | 3 ++- 2 files changed, 3 insertions(+), 2 deletions(-)
diff --git a/drivers/net/mctp/mctp-usb.c b/drivers/net/mctp/mctp-usb.c
index 545eff06322c..c6e36b63e87a 100644
--- a/drivers/net/mctp/mctp-usb.c
+++ b/drivers/net/mctp/mctp-usb.c@@ -76,7 +76,7 @@ static netdev_tx_t mctp_usb_start_xmit(struct sk_buff *skb, plen = skb->len; - if (plen + sizeof(*hdr) > MCTP_USB_1_0_XFER_SIZE) + if (plen + sizeof(*hdr) > MCTP_USB_1_0_PKTLEN_MAX) goto err_drop; rc = skb_cow_head(skb, sizeof(*hdr));
diff --git a/include/linux/usb/mctp-usb.h b/include/linux/usb/mctp-usb.h
index 47e2e3931d63..2bece8afd1c7 100644
--- a/include/linux/usb/mctp-usb.h
+++ b/include/linux/usb/mctp-usb.h@@ -25,7 +25,8 @@ struct mctp_usb_hdr { #define MCTP_USB_1_0_XFER_SIZE 512 #define MCTP_USB_BTU 68 #define MCTP_USB_MTU_MIN MCTP_USB_BTU -#define MCTP_USB_1_0_MTU_MAX (U8_MAX - sizeof(struct mctp_usb_hdr)) +#define MCTP_USB_1_0_PKTLEN_MAX U8_MAX +#define MCTP_USB_1_0_MTU_MAX (MCTP_USB_1_0_PKTLEN_MAX - sizeof(struct mctp_usb_hdr)) #define MCTP_USB_DMTF_ID 0x1ab4 #endif /* __LINUX_USB_MCTP_USB_H */
--
2.47.3