From: Muhammad Sammar muhammads@mellanox.com
[ Upstream commit 142a9c287613560edf5a03c8d142c8b6ebc1995b ]
It is illegal to change MTU to a value lower than the minimum MTU stated in ethernet spec. In addition to that we need to add 4 bytes for encapsulation header (IPOIB_ENCAP_LEN).
Before "ifconfig ib0 mtu 0" command, succeeds while it obviously shouldn't.
Signed-off-by: Muhammad Sammar muhammads@mellanox.com Reviewed-by: Feras Daoud ferasda@mellanox.com Signed-off-by: Leon Romanovsky leonro@mellanox.com Signed-off-by: Jason Gunthorpe jgg@mellanox.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/infiniband/ulp/ipoib/ipoib_main.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/infiniband/ulp/ipoib/ipoib_main.c b/drivers/infiniband/ulp/ipoib/ipoib_main.c index 1a93d3d58c8a4..caae4bfab950d 100644 --- a/drivers/infiniband/ulp/ipoib/ipoib_main.c +++ b/drivers/infiniband/ulp/ipoib/ipoib_main.c @@ -249,7 +249,8 @@ static int ipoib_change_mtu(struct net_device *dev, int new_mtu) return 0; }
- if (new_mtu > IPOIB_UD_MTU(priv->max_ib_mtu)) + if (new_mtu < (ETH_MIN_MTU + IPOIB_ENCAP_LEN) || + new_mtu > IPOIB_UD_MTU(priv->max_ib_mtu)) return -EINVAL;
priv->admin_mtu = new_mtu;