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Commit 4d565f46 authored by Xie He's avatar Xie He Committed by Greg Kroah-Hartman
Browse files

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



[ Upstream commit 9dc829a135fb5927f1519de11286e2bbb79f5b66 ]

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: default avatarXie He <xie.he.0141@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent 55ba6c92

drivers/net/wan/lapbether.c

+8 −1
Original line number Diff line number Diff line
@@ -308,7 +308,6 @@ static void lapbeth_setup(struct net_device *dev) 
	dev->netdev_ops	     = &lapbeth_netdev_ops;

	dev->destructor	     = free_netdev;

	dev->type            = ARPHRD_X25;

	dev->hard_header_len = 3;

	dev->mtu             = 1000;

	dev->addr_len        = 0;

}
@@ -329,6 +328,14 @@ 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;