Since commit 8df9ffb888c ("can: make use of preallocated can_ml_priv for per
device struct can_dev_rcv_lists") the device specific CAN receive filter lists
are stored in netdev_priv() and dev->ml_priv points to these filters.
In the bug report Syzkaller enslaved a vxcan1 CAN device and accessed the
bonding device with a PF_CAN socket which lead to a crash due to an access of
an unhandled bond_dev->ml_priv pointer.
Deny to enslave CAN devices by the bonding driver as the resulting bond_dev
pretends to be a CAN device by copying dev->type without really being one.
Reported-by: syzbot+c3ea30e1e2485573f953@xxxxxxxxxxxxxxxxxxxxxxxxx
Fixes: 8df9ffb888c ("can: make use of preallocated can_ml_priv for per
device struct can_dev_rcv_lists")
Cc: linux-stable <stable@xxxxxxxxxxxxxxx> # >= v5.4
Signed-off-by: Oliver Hartkopp <socketcan@xxxxxxxxxxxx>
---
drivers/net/bonding/bond_main.c | 12 ++++++++++++
1 file changed, 12 insertions(+)
diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
index 48d5ec770b94..4b781a7dfd96 100644
--- a/drivers/net/bonding/bond_main.c
+++ b/drivers/net/bonding/bond_main.c
@@ -1475,6 +1475,18 @@ int bond_enslave(struct net_device *bond_dev, struct net_device *slave_dev,
return -EPERM;
}
+ /* CAN network devices hold device specific filter lists in
+ * netdev_priv() where dev->ml_priv sets a reference to.
+ * As bonding assumes to have some ethernet-like device it doesn't
+ * take care about these CAN specific filter lists today.
+ * So we deny the enslaving of CAN interfaces here.
+ */
+ if (slave_dev->type == ARPHRD_CAN) {
+ NL_SET_ERR_MSG(extack, "CAN devices can not be enslaved");
+ slave_err(bond_dev, slave_dev, "no bonding on CAN devices\n");
+ return -EINVAL;
+ }
+
/* set bonding device ether type by slave - bonding netdevices are
* created with ether_setup, so when the slave type is not ARPHRD_ETHER
* there is a need to override some of the type dependent attribs/funcs.
--
2.20.1
