[PATCH 1/1] RDMA/ionic: Preserve and set Ethernet source MAC after ib_ud_header_init()

[Abhijit Gangurde <abhijit.gangurde@amd.com>]

ionic_build_hdr() populated the Ethernet source MAC (hdr->eth.smac_h) by
passing the header’s storage directly to rdma_read_gid_l2_fields().
However, ib_ud_header_init() is called after that and re-initializes the
UD header, which wipes the previously written smac_h. As a result, packets
are emitted with an zero source MAC address on the wire.

Correct the source MAC by reading the GID-derived smac into a temporary
buffer and copy it after ib_ud_header_init() completes.

Fixes: e8521822c733 ("RDMA/ionic: Register device ops for control path")
Cc: stable@vger.kernel.org # 6.18
Signed-off-by: Abhijit Gangurde <abhijit.gangurde@amd.com>
---
 drivers/infiniband/hw/ionic/ionic_controlpath.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/infiniband/hw/ionic/ionic_controlpath.c b/drivers/infiniband/hw/ionic/ionic_controlpath.c
index ea12d9b8e125..84bc5f17a700 100644
--- a/drivers/infiniband/hw/ionic/ionic_controlpath.c
+++ b/drivers/infiniband/hw/ionic/ionic_controlpath.c
@@ -508,6 +508,7 @@ static int ionic_build_hdr(struct ionic_ibdev *dev,
 {
 	const struct ib_global_route *grh;
 	enum rdma_network_type net;
+	u8 smac[ETH_ALEN];
 	u16 vlan;
 	int rc;
 
@@ -518,7 +519,7 @@ static int ionic_build_hdr(struct ionic_ibdev *dev,
 
 	grh = rdma_ah_read_grh(attr);
 
-	rc = rdma_read_gid_l2_fields(grh->sgid_attr, &vlan, &hdr->eth.smac_h[0]);
+	rc = rdma_read_gid_l2_fields(grh->sgid_attr, &vlan, smac);
 	if (rc)
 		return rc;
 
@@ -536,6 +537,7 @@ static int ionic_build_hdr(struct ionic_ibdev *dev,
 	if (rc)
 		return rc;
 
+	ether_addr_copy(hdr->eth.smac_h, smac);
 	ether_addr_copy(hdr->eth.dmac_h, attr->roce.dmac);
 
 	if (net == RDMA_NETWORK_IPV4) {
-- 
2.43.0