The following commit has been merged in the master branch: commit ed7809d9c41b514115ddffaa860694393c2016b3 Author: Jesper Juhl jj@chaosbits.net Date: Thu Jan 13 21:53:38 2011 +0100

batman-adv: Even Batman should not dereference NULL pointers

There's a problem in net/batman-adv/unicast.c::frag_send_skb(). dev_alloc_skb() allocates memory and may fail, thus returning NULL. If this happens we'll pass a NULL pointer on to skb_split() which in turn hands it to skb_split_inside_header() from where it gets passed to skb_put() that lets skb_tail_pointer() play with it and that function dereferences it. And thus the bat dies.

While I was at it I also moved the call to dev_alloc_skb() above the assignment to 'unicast_packet' since there's no reason to do that assignment if the memory allocation fails.

Signed-off-by: Jesper Juhl jj@chaosbits.net Signed-off-by: Sven Eckelmann sven@narfation.org

diff --git a/net/batman-adv/unicast.c b/net/batman-adv/unicast.c index dc2e28b..ee41fef 100644 --- a/net/batman-adv/unicast.c +++ b/net/batman-adv/unicast.c @@ -229,10 +229,12 @@ int frag_send_skb(struct sk_buff *skb, struct bat_priv *bat_priv, if (!bat_priv->primary_if) goto dropped;

- unicast_packet = (struct unicast_packet *) skb->data; + frag_skb = dev_alloc_skb(data_len - (data_len / 2) + ucf_hdr_len); + if (!frag_skb) + goto dropped;

+ unicast_packet = (struct unicast_packet *) skb->data; memcpy(&tmp_uc, unicast_packet, uc_hdr_len); - frag_skb = dev_alloc_skb(data_len - (data_len / 2) + ucf_hdr_len); skb_split(skb, frag_skb, data_len / 2);

if (my_skb_head_push(skb, ucf_hdr_len - uc_hdr_len) < 0 ||