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: c91a4f9feb67 ("iavf: add support for UDP Segmentation Offload")
Reviewed-by: Eric Dumazet <[email protected]>
Reviewed-by: Maciej Fijalkowski <[email protected]>
Signed-off-by: Magnus Karlsson <[email protected]>
---
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
