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batman-adv: fix potential kernel paging errors for unicast transmissions

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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@web.de>
Signed-off-by: Marek Lindner <lindner_marek@yahoo.de>
Signed-off-by: Antonio Quartulli <ordex@autistici.org>
This commit is contained in:
Linus Lüssing 2013-08-06 20:21:15 +02:00 committed by Antonio Quartulli
parent 6453599302
commit 9d2c9488ce
5 changed files with 33 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
net/batman-adv/bridge_loop_avoidance.c
View File

@ -1529,6 +1529,8 @@ int batadv_bla_rx(struct batadv_priv *bat_priv, struct sk_buff *skb,
* 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)

13
net/batman-adv/gateway_client.c
View File

@ -508,6 +508,7 @@ int batadv_gw_client_seq_print_text(struct seq_file *seq, void *offset)
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 @@ static bool batadv_is_type_dhcprequest(struct sk_buff *skb, int header_len)
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)

3
net/batman-adv/gateway_client.h
View File

@ -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_ */

9
net/batman-adv/soft-interface.c
View File

@ -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;
}

13
net/batman-adv/unicast.c
View File

@ -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 @@ int batadv_unicast_generic_send_skb(struct batadv_priv *bat_priv,
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 @@ int batadv_unicast_generic_send_skb(struct batadv_priv *bat_priv,
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