[linux-next] LinuxNextTracking branch, master, updated. next-20110624

batman at open-mesh.org batman at open-mesh.org
Fri Jun 24 16:08:49 CEST 2011

The following commit has been merged in the master branch:
commit ed7809d9c41b514115ddffaa860694393c2016b3
Author: Jesper Juhl <jj at 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 at chaosbits.net>
    Signed-off-by: Sven Eckelmann <sven at 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 ||


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