The following commit has been merged in the next branch: commit 50d7c5a968cde5ea638fbb945135ea7c4ed90733 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/unicast.c b/unicast.c index dc2e28b..ee41fef 100644 --- a/unicast.c +++ b/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 ||