From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: =?UTF-8?q?Linus=20L=C3=BCssing?= Date: Fri, 26 Jul 2013 20:50:46 +0200 Message-Id: <1374864646-19268-2-git-send-email-linus.luessing@web.de> In-Reply-To: <1374864646-19268-1-git-send-email-linus.luessing@web.de> References: <1374864646-19268-1-git-send-email-linus.luessing@web.de> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit Subject: [B.A.T.M.A.N.] [PATCH 2/2] batman-adv: fix potential kernel paging error for unicast transmissions Reply-To: The list for a Better Approach To Mobile Ad-hoc Networking List-Id: The list for a Better Approach To Mobile Ad-hoc Networking List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: b.a.t.m.a.n@lists.open-mesh.org 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. This patch fixes this issue by storing the few bytes we are interested in on the stack before modifying the skb. Signed-off-by: Linus Lüssing --- send.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/send.c b/send.c index 9c9cab6..b9a1f15 100644 --- a/send.c +++ b/send.c @@ -257,13 +257,15 @@ 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; + uint8_t dest[ETH_ALEN]; struct batadv_unicast_packet *unicast_packet; int ret = NET_XMIT_DROP; if (!orig_node) goto out; + memcpy(dest, ((struct ethhdr *)skb->data)->h_dest, sizeof(dest)); + switch (packet_type) { case BATADV_UNICAST: if (!batadv_send_skb_prepare_unicast(skb, orig_node)) @@ -289,7 +291,7 @@ static int batadv_send_skb_unicast(struct batadv_priv *bat_priv, * try to reroute it because the ttvn contained in the header is less * than the current one */ - if (batadv_tt_global_client_is_roaming(bat_priv, ethhdr->h_dest, vid)) + if (batadv_tt_global_client_is_roaming(bat_priv, dest, vid)) unicast_packet->ttvn = unicast_packet->ttvn - 1; if (batadv_send_skb_to_orig(skb, orig_node, NULL) != NET_XMIT_DROP) -- 1.7.10.4