diff mbox

[v2,next] batman-adv: fix potential kernel paging error for unicast transmissions

Message ID 1390173968-8670-1-git-send-email-linus.luessing@web.de (mailing list archive)
State Superseded, archived
Headers

Commit Message

Linus Lüssing Jan. 19, 2014, 11:26 p.m. UTC 
  batadv_send_skb_prepare_unicast(_4addr) might reallocate the skb's
data. If it does then our ethhdr pointer is not valid anymore in
batadv_send_skb_unicast(), resulting in a kernel paging error.

Fixing this by refetching the ethhdr pointer after the potential
reallocation.

~~~
NOTE TO LINUX STABLE MAINTAINERS:

For kernels < 3.9 you will need an additional skb_reset_mac_header(skb)
call in the beginning of batadv_send_skb_unicast().

For kernels >= 3.9 this is not necessary thanks to:

"net: reset mac header in dev_start_xmit()" (6d1ccff627)
~~~

Signed-off-by: Linus Lüssing <linus.luessing@web.de>
---
Note: this patch shouldn't be used in an off-tree module on
kernels < 3.9 without the compat hunk provided by:

"batman-adv: use vlan_/eth_hdr() instead of skb->data in interface_tx path"


 send.c |    4 ++++
 1 file changed, 4 insertions(+)
diff mbox

Patch

diff --git a/send.c b/send.c
index 579f5f0..8b312e3 100644
--- a/send.c
+++ b/send.c
@@ -279,6 +279,10 @@  static int batadv_send_skb_unicast(struct batadv_priv *bat_priv,
 		goto out;
 	}
 
+	/* skb->data might have been reallocated by
+	 * batadv_send_skb_prepare_unicast*
+	 */
+	ethhdr = eth_hdr(skb);
 	unicast_packet = (struct batadv_unicast_packet *)skb->data;
 
 	/* inform the destination node that we are still missing a correct route