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drivers/net/wan/lapbether: Fixed the value of hard_header_len 

[ Upstream commit 9dc829a135 ]

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>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Xie He 2020-07-05 17:45:21 -07:00 committed by Greg Kroah-Hartman
parent 0eced76360
commit e50116e512
1 changed files with 8 additions and 1 deletions
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9
drivers/net/wan/lapbether.c
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@ -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;