From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sven Eckelmann Subject: [PATCH 1/2] batman-adv: Even Batman should not dereference NULL pointers Date: Sun, 16 Jan 2011 03:38:46 +0100 Message-ID: <1295145527-17537-2-git-send-email-sven@narfation.org> References: <1295145527-17537-1-git-send-email-sven@narfation.org> Reply-To: The list for a Better Approach To Mobile Ad-hoc Networking Cc: netdev-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, b.a.t.m.a.n-ZwoEplunGu2X36UT3dwllkB+6BGkLq7r@public.gmane.org, Jesper Juhl To: davem-fT/PcQaiUtIeIZ0/mPfg9Q@public.gmane.org Return-path: In-Reply-To: <1295145527-17537-1-git-send-email-sven-KaDOiPu9UxWEi8DpZVb4nw@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: b.a.t.m.a.n-bounces-ZwoEplunGu2X36UT3dwllkB+6BGkLq7r@public.gmane.org Errors-To: b.a.t.m.a.n-bounces-ZwoEplunGu2X36UT3dwllkB+6BGkLq7r@public.gmane.org List-Id: netdev.vger.kernel.org From: Jesper Juhl 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 Signed-off-by: Sven Eckelmann --- net/batman-adv/unicast.c | 6 ++++-- 1 files changed, 4 insertions(+), 2 deletions(-) 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 || -- 1.7.2.3