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Commit 0ff0f15a authored by Sven Eckelmann's avatar Sven Eckelmann Committed by Simon Wunderlich
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batman-adv: Only read OGM2 tvlv_len after buffer len check 



Multiple batadv_ogm2_packet can be stored in an skbuff. The functions
batadv_v_ogm_send_to_if() uses batadv_v_ogm_aggr_packet() to check if there
is another additional batadv_ogm2_packet in the skb or not before they
continue processing the packet.

The length for such an OGM2 is BATADV_OGM2_HLEN +
batadv_ogm2_packet->tvlv_len. The check must first check that at least
BATADV_OGM2_HLEN bytes are available before it accesses tvlv_len (which is
part of the header. Otherwise it might try read outside of the currently
available skbuff to get the content of tvlv_len.

Fixes: 9323158e ("batman-adv: OGMv2 - implement originators logic")
Signed-off-by: default avatarSven Eckelmann <sven@narfation.org>
Signed-off-by: default avatarSimon Wunderlich <sw@simonwunderlich.de>
parent a15d56a6

net/batman-adv/bat_v_ogm.c

+12 −6
Original line number Diff line number Diff line
@@ -631,17 +631,23 @@ batadv_v_ogm_process_per_outif(struct batadv_priv *bat_priv, 
 * batadv_v_ogm_aggr_packet() - checks if there is another OGM aggregated

 * @buff_pos: current position in the skb

 * @packet_len: total length of the skb

 * @tvlv_len: tvlv length of the previously considered OGM

 * @ogm2_packet: potential OGM2 in buffer

 *

 * Return: true if there is enough space for another OGM, false otherwise.

 */

static bool batadv_v_ogm_aggr_packet(int buff_pos, int packet_len,

				     __be16 tvlv_len)

static bool

batadv_v_ogm_aggr_packet(int buff_pos, int packet_len,

			 const struct batadv_ogm2_packet *ogm2_packet)

{

	int next_buff_pos = 0;



	next_buff_pos += buff_pos + BATADV_OGM2_HLEN;

	next_buff_pos += ntohs(tvlv_len);

	/* check if there is enough space for the header */

	next_buff_pos += buff_pos + sizeof(*ogm2_packet);

	if (next_buff_pos > packet_len)

		return false;



	/* check if there is enough space for the optional TVLV */

	next_buff_pos += ntohs(ogm2_packet->tvlv_len);



	return (next_buff_pos <= packet_len) &&

	       (next_buff_pos <= BATADV_MAX_AGGREGATION_BYTES);
@@ -818,7 +824,7 @@ int batadv_v_ogm_packet_recv(struct sk_buff *skb, 
	ogm_packet = (struct batadv_ogm2_packet *)skb->data;



	while (batadv_v_ogm_aggr_packet(ogm_offset, skb_headlen(skb),

					ogm_packet->tvlv_len)) {

					ogm_packet)) {

		batadv_v_ogm_process(skb, ogm_offset, if_incoming);



		ogm_offset += BATADV_OGM2_HLEN;