| Message ID | 20200706004521.78091-1-xie.he.0141@gmail.com |
|---|---|
| State | Accepted |
| Delegated to: | David Miller |
| Headers | show |
| Series | [v2] drivers/net/wan/lapbether: Fixed the value of hard_header_len | expand |
From: Xie He <xie.he.0141@gmail.com> Date: Sun, 5 Jul 2020 17:45:21 -0700 > When this driver transmits data, > first this driver will remove a pseudo header of 1 byte, > then the lapb module will prepend the LAPB header of 2 or 3 bytes, > then this driver will prepend a length field of 2 bytes, > then the underlying Ethernet device will prepend its own header. > > So, the header length required should be: > -1 + 3 + 2 + "the header length needed by the underlying device". > > This patch fixes kernel panic when this driver is used with AF_PACKET > SOCK_DGRAM sockets. > > Signed-off-by: Xie He <xie.he.0141@gmail.com> Applied, thank you.
diff --git a/drivers/net/wan/lapbether.c b/drivers/net/wan/lapbether.c index e30d91a38cfb..284832314f31 100644 --- a/drivers/net/wan/lapbether.c +++ b/drivers/net/wan/lapbether.c @@ -303,7 +303,6 @@ static void lapbeth_setup(struct net_device *dev) dev->netdev_ops = &lapbeth_netdev_ops; dev->needs_free_netdev = true; dev->type = ARPHRD_X25; - dev->hard_header_len = 3; dev->mtu = 1000; dev->addr_len = 0; } @@ -324,6 +323,14 @@ static int lapbeth_new_device(struct net_device *dev) if (!ndev) goto out; + /* When transmitting data: + * first this driver removes a pseudo header of 1 byte, + * then the lapb module prepends an LAPB header of at most 3 bytes, + * then this driver prepends a length field of 2 bytes, + * then the underlying Ethernet device prepends its own header. + */ + ndev->hard_header_len = -1 + 3 + 2 + dev->hard_header_len; + lapbeth = netdev_priv(ndev); lapbeth->axdev = ndev;
When this driver transmits data, first this driver will remove a pseudo header of 1 byte, then the lapb module will prepend the LAPB header of 2 or 3 bytes, then this driver will prepend a length field of 2 bytes, then the underlying Ethernet device will prepend its own header. So, the header length required should be: -1 + 3 + 2 + "the header length needed by the underlying device". This patch fixes kernel panic when this driver is used with AF_PACKET SOCK_DGRAM sockets. Signed-off-by: Xie He <xie.he.0141@gmail.com> --- Change in v2: added a comment in the code drivers/net/wan/lapbether.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-)