bonding: set random address only when slaves already exist

[ Upstream commit 35ae4e86292ef7dfe4edbb9942955c884e984352 ]

After commit 5c3bf6cba791 ("bonding: assign random address if device
address is same as bond"), bonding will erroneously randomize the MAC
address of the first interface added to the bond if fail_over_mac =
follow.

Correct this by additionally testing for the bond being empty before
randomizing the MAC.

Fixes: 5c3bf6cba791 ("bonding: assign random address if device address is same as bond")
Reported-by: Qiuling Ren <qren@redhat.com>
Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
Link: https://patch.msgid.link/20250910024336.400253-1-liuhangbin@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
index 52ff0f9e04e0793336b1efaf126328ec28cd8c89..952737a98751e237b119d1d49013cc483b505db8 100644 (file)
--- a/drivers/net/bonding/bond_main.c
+++ b/drivers/net/bonding/bond_main.c
@@ -2117,6 +2117,7 @@ int bond_enslave(struct net_device *bond_dev, struct net_device *slave_dev,
                memcpy(ss.__data, bond_dev->dev_addr, bond_dev->addr_len);
        } else if (bond->params.fail_over_mac == BOND_FOM_FOLLOW &&
                   BOND_MODE(bond) == BOND_MODE_ACTIVEBACKUP &&
+                  bond_has_slaves(bond) &&
                   memcmp(slave_dev->dev_addr, bond_dev->dev_addr, bond_dev->addr_len) == 0) {
                /* Set slave to random address to avoid duplicate mac
                 * address in later fail over.