[PATCH iwl-net 2/2] iavf: fix USO for 32-bit systems

That USO works for 64-bit systems is just pure luck. Currently, the
computation of the UDP segmentation header is performed using sizeof()
a pointer instead of the sizeof() the UDP header that the pointer
points to. Since the UDP header happens to be 8 bytes long and a
pointer is 8 bytes long on a 64-bit system, this works on all those
systems. But no such luck for anyone using a 32-bit system as 8 bytes
!= 4 bytes. So fix this by using sizeof() the UDP header that the
pointer points to instead.

This was found by an LLM while implementing something else that used USO.

Fixes: c91a4f9feb67a199c2 ("add support for UDP Segmentation Offload")
Signed-off-by: Magnus Karlsson <magnus.karlsson@intel.com>
---
 drivers/net/ethernet/intel/iavf/iavf_txrx.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/intel/iavf/iavf_txrx.c b/drivers/net/ethernet/intel/iavf/iavf_txrx.c
index 8982cf75466f..2c290d7788d2 100644
--- a/drivers/net/ethernet/intel/iavf/iavf_txrx.c
+++ b/drivers/net/ethernet/intel/iavf/iavf_txrx.c

@@ -1807,7 +1807,7 @@ static int iavf_tso(struct iavf_tx_buffer *first, u8 *hdr_len,
 		csum_replace_by_diff(&l4.udp->check,
 				     (__force __wsum)htonl(paylen));
 		/* compute length of UDP segmentation header */
-		*hdr_len = (u8)sizeof(l4.udp) + l4_offset;
+		*hdr_len = sizeof(*l4.udp) + l4_offset;
 	} else {
 		csum_replace_by_diff(&l4.tcp->check,
 				     (__force __wsum)htonl(paylen));

-- 
2.38.1