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Date: Sat, 10 Aug 2013 23:08:01 +0200
From: Antonio Quartulli <ordex@...istici.org>
To: davem@...emloft.net
Cc: netdev@...r.kernel.org, b.a.t.m.a.n@...ts.open-mesh.org,
Linus Lüssing <linus.luessing@....de>,
Marek Lindner <lindner_marek@...oo.de>,
Antonio Quartulli <ordex@...istici.org>
Subject: [PATCH] batman-adv: fix potential kernel paging errors for unicast transmissions
From: Linus Lüssing <linus.luessing@....de>
There are several functions which might reallocate skb data. Currently
some places keep reusing their old ethhdr pointer regardless of whether
they became invalid after such a reallocation or not. This potentially
leads to kernel paging errors.
This patch fixes these by refetching the ethdr pointer after the
potential reallocations.
Signed-off-by: Linus Lüssing <linus.luessing@....de>
Signed-off-by: Marek Lindner <lindner_marek@...oo.de>
Signed-off-by: Antonio Quartulli <ordex@...istici.org>
---
net/batman-adv/bridge_loop_avoidance.c | 2 ++
net/batman-adv/gateway_client.c | 13 ++++++++++++-
net/batman-adv/gateway_client.h | 3 +--
net/batman-adv/soft-interface.c | 9 ++++++++-
net/batman-adv/unicast.c | 13 ++++++++++---
5 files changed, 33 insertions(+), 7 deletions(-)
diff --git a/net/batman-adv/bridge_loop_avoidance.c b/net/batman-adv/bridge_loop_avoidance.c
index e14531f..264de88 100644
--- a/net/batman-adv/bridge_loop_avoidance.c
+++ b/net/batman-adv/bridge_loop_avoidance.c
@@ -1529,6 +1529,8 @@ out:
* in these cases, the skb is further handled by this function and
* returns 1, otherwise it returns 0 and the caller shall further
* process the skb.
+ *
+ * This call might reallocate skb data.
*/
int batadv_bla_tx(struct batadv_priv *bat_priv, struct sk_buff *skb,
unsigned short vid)
diff --git a/net/batman-adv/gateway_client.c b/net/batman-adv/gateway_client.c
index f105219..7614af3 100644
--- a/net/batman-adv/gateway_client.c
+++ b/net/batman-adv/gateway_client.c
@@ -508,6 +508,7 @@ out:
return 0;
}
+/* this call might reallocate skb data */
static bool batadv_is_type_dhcprequest(struct sk_buff *skb, int header_len)
{
int ret = false;
@@ -568,6 +569,7 @@ out:
return ret;
}
+/* this call might reallocate skb data */
bool batadv_gw_is_dhcp_target(struct sk_buff *skb, unsigned int *header_len)
{
struct ethhdr *ethhdr;
@@ -619,6 +621,12 @@ bool batadv_gw_is_dhcp_target(struct sk_buff *skb, unsigned int *header_len)
if (!pskb_may_pull(skb, *header_len + sizeof(*udphdr)))
return false;
+
+ /* skb->data might have been reallocated by pskb_may_pull() */
+ ethhdr = (struct ethhdr *)skb->data;
+ if (ntohs(ethhdr->h_proto) == ETH_P_8021Q)
+ ethhdr = (struct ethhdr *)(skb->data + VLAN_HLEN);
+
udphdr = (struct udphdr *)(skb->data + *header_len);
*header_len += sizeof(*udphdr);
@@ -634,12 +642,14 @@ bool batadv_gw_is_dhcp_target(struct sk_buff *skb, unsigned int *header_len)
return true;
}
+/* this call might reallocate skb data */
bool batadv_gw_out_of_range(struct batadv_priv *bat_priv,
- struct sk_buff *skb, struct ethhdr *ethhdr)
+ struct sk_buff *skb)
{
struct batadv_neigh_node *neigh_curr = NULL, *neigh_old = NULL;
struct batadv_orig_node *orig_dst_node = NULL;
struct batadv_gw_node *curr_gw = NULL;
+ struct ethhdr *ethhdr;
bool ret, out_of_range = false;
unsigned int header_len = 0;
uint8_t curr_tq_avg;
@@ -648,6 +658,7 @@ bool batadv_gw_out_of_range(struct batadv_priv *bat_priv,
if (!ret)
goto out;
+ ethhdr = (struct ethhdr *)skb->data;
orig_dst_node = batadv_transtable_search(bat_priv, ethhdr->h_source,
ethhdr->h_dest);
if (!orig_dst_node)
diff --git a/net/batman-adv/gateway_client.h b/net/batman-adv/gateway_client.h
index 039902d..1037d75 100644
--- a/net/batman-adv/gateway_client.h
+++ b/net/batman-adv/gateway_client.h
@@ -34,7 +34,6 @@ void batadv_gw_node_delete(struct batadv_priv *bat_priv,
void batadv_gw_node_purge(struct batadv_priv *bat_priv);
int batadv_gw_client_seq_print_text(struct seq_file *seq, void *offset);
bool batadv_gw_is_dhcp_target(struct sk_buff *skb, unsigned int *header_len);
-bool batadv_gw_out_of_range(struct batadv_priv *bat_priv,
- struct sk_buff *skb, struct ethhdr *ethhdr);
+bool batadv_gw_out_of_range(struct batadv_priv *bat_priv, struct sk_buff *skb);
#endif /* _NET_BATMAN_ADV_GATEWAY_CLIENT_H_ */
diff --git a/net/batman-adv/soft-interface.c b/net/batman-adv/soft-interface.c
index 700d0b4..0f04e1c 100644
--- a/net/batman-adv/soft-interface.c
+++ b/net/batman-adv/soft-interface.c
@@ -180,6 +180,9 @@ static int batadv_interface_tx(struct sk_buff *skb,
if (batadv_bla_tx(bat_priv, skb, vid))
goto dropped;
+ /* skb->data might have been reallocated by batadv_bla_tx() */
+ ethhdr = (struct ethhdr *)skb->data;
+
/* Register the client MAC in the transtable */
if (!is_multicast_ether_addr(ethhdr->h_source))
batadv_tt_local_add(soft_iface, ethhdr->h_source, skb->skb_iif);
@@ -220,6 +223,10 @@ static int batadv_interface_tx(struct sk_buff *skb,
default:
break;
}
+
+ /* reminder: ethhdr might have become unusable from here on
+ * (batadv_gw_is_dhcp_target() might have reallocated skb data)
+ */
}
/* ethernet packet should be broadcasted */
@@ -266,7 +273,7 @@ static int batadv_interface_tx(struct sk_buff *skb,
/* unicast packet */
} else {
if (atomic_read(&bat_priv->gw_mode) != BATADV_GW_MODE_OFF) {
- ret = batadv_gw_out_of_range(bat_priv, skb, ethhdr);
+ ret = batadv_gw_out_of_range(bat_priv, skb);
if (ret)
goto dropped;
}
diff --git a/net/batman-adv/unicast.c b/net/batman-adv/unicast.c
index dc8b5d4..688a041 100644
--- a/net/batman-adv/unicast.c
+++ b/net/batman-adv/unicast.c
@@ -326,7 +326,9 @@ static bool batadv_unicast_push_and_fill_skb(struct sk_buff *skb, int hdr_size,
* @skb: the skb containing the payload to encapsulate
* @orig_node: the destination node
*
- * Returns false if the payload could not be encapsulated or true otherwise
+ * Returns false if the payload could not be encapsulated or true otherwise.
+ *
+ * This call might reallocate skb data.
*/
static bool batadv_unicast_prepare_skb(struct sk_buff *skb,
struct batadv_orig_node *orig_node)
@@ -343,7 +345,9 @@ static bool batadv_unicast_prepare_skb(struct sk_buff *skb,
* @orig_node: the destination node
* @packet_subtype: the batman 4addr packet subtype to use
*
- * Returns false if the payload could not be encapsulated or true otherwise
+ * Returns false if the payload could not be encapsulated or true otherwise.
+ *
+ * This call might reallocate skb data.
*/
bool batadv_unicast_4addr_prepare_skb(struct batadv_priv *bat_priv,
struct sk_buff *skb,
@@ -401,7 +405,7 @@ int batadv_unicast_generic_send_skb(struct batadv_priv *bat_priv,
struct batadv_neigh_node *neigh_node;
int data_len = skb->len;
int ret = NET_RX_DROP;
- unsigned int dev_mtu;
+ unsigned int dev_mtu, header_len;
/* get routing information */
if (is_multicast_ether_addr(ethhdr->h_dest)) {
@@ -429,10 +433,12 @@ find_router:
switch (packet_type) {
case BATADV_UNICAST:
batadv_unicast_prepare_skb(skb, orig_node);
+ header_len = sizeof(struct batadv_unicast_packet);
break;
case BATADV_UNICAST_4ADDR:
batadv_unicast_4addr_prepare_skb(bat_priv, skb, orig_node,
packet_subtype);
+ header_len = sizeof(struct batadv_unicast_4addr_packet);
break;
default:
/* this function supports UNICAST and UNICAST_4ADDR only. It
@@ -441,6 +447,7 @@ find_router:
goto out;
}
+ ethhdr = (struct ethhdr *)(skb->data + header_len);
unicast_packet = (struct batadv_unicast_packet *)skb->data;
/* inform the destination node that we are still missing a correct route
--
1.8.1.5
--
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