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batman-adv: fix potential kernel paging error for unicast transmissions

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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.

Signed-off-by: Linus Lüssing <linus.luessing@web.de>
Signed-off-by: Antonio Quartulli <antonio@meshcoding.com>
This commit is contained in:
Antonio Quartulli 2014-02-15 21:50:37 +01:00
parent a5a5cb8cab
commit 70b271a78b
1 changed files with 7 additions and 2 deletions
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9
net/batman-adv/send.c
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@ -254,9 +254,9 @@ static int batadv_send_skb_unicast(struct batadv_priv *bat_priv,
struct batadv_orig_node *orig_node,
unsigned short vid)
{
struct ethhdr *ethhdr = (struct ethhdr *)skb->data;
struct ethhdr *ethhdr;
struct batadv_unicast_packet *unicast_packet;
int ret = NET_XMIT_DROP;
int ret = NET_XMIT_DROP, hdr_size;
if (!orig_node)
goto out;
@ -265,12 +265,16 @@ static int batadv_send_skb_unicast(struct batadv_priv *bat_priv,
case BATADV_UNICAST:
if (!batadv_send_skb_prepare_unicast(skb, orig_node))
goto out;
hdr_size = sizeof(*unicast_packet);
break;
case BATADV_UNICAST_4ADDR:
if (!batadv_send_skb_prepare_unicast_4addr(bat_priv, skb,
orig_node,
packet_subtype))
goto out;
hdr_size = sizeof(struct batadv_unicast_4addr_packet);
break;
default:
/* this function supports UNICAST and UNICAST_4ADDR only. It
@ -279,6 +283,7 @@ static int batadv_send_skb_unicast(struct batadv_priv *bat_priv,
goto out;
}
ethhdr = (struct ethhdr *)(skb->data + hdr_size);
unicast_packet = (struct batadv_unicast_packet *)skb->data;
/* inform the destination node that we are still missing a correct route