3.16.78-rc1 review patch. If anyone has any objections, please let me know.
------------------
From: Sven Eckelmann <sven@xxxxxxxxxxxxx>
commit a15d56a60760aa9dbe26343b9a0ac5228f35d445 upstream.
Multiple batadv_ogm_packet can be stored in an skbuff. The functions
batadv_iv_ogm_send_to_if()/batadv_iv_ogm_receive() use
batadv_iv_ogm_aggr_packet() to check if there is another additional
batadv_ogm_packet in the skb or not before they continue processing the
packet.
The length for such an OGM is BATADV_OGM_HLEN +
batadv_ogm_packet->tvlv_len. The check must first check that at least
BATADV_OGM_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: ef26157747d4 ("batman-adv: tvlv - basic infrastructure")
Reported-by: syzbot+355cab184197dbbfa384@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Sven Eckelmann <sven@xxxxxxxxxxxxx>
Acked-by: Antonio Quartulli <a@xxxxxxxxxxx>
Signed-off-by: Simon Wunderlich <sw@xxxxxxxxxxxxxxxxxx>
[bwh: Backported to 3.16:
- Drop kernel-doc change
- Adjust context]
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
--- a/net/batman-adv/bat_iv_ogm.c
+++ b/net/batman-adv/bat_iv_ogm.c
@@ -395,13 +395,19 @@ static uint8_t batadv_hop_penalty(uint8_
}
/* is there another aggregated packet here? */
-static int batadv_iv_ogm_aggr_packet(int buff_pos, int packet_len,
- __be16 tvlv_len)
+static bool
+batadv_iv_ogm_aggr_packet(int buff_pos, int packet_len,
+ const struct batadv_ogm_packet *ogm_packet)
{
int next_buff_pos = 0;
- next_buff_pos += buff_pos + BATADV_OGM_HLEN;
- next_buff_pos += ntohs(tvlv_len);
+ /* check if there is enough space for the header */
+ next_buff_pos += buff_pos + sizeof(*ogm_packet);
+ if (next_buff_pos > packet_len)
+ return false;
+
+ /* check if there is enough space for the optional TVLV */
+ next_buff_pos += ntohs(ogm_packet->tvlv_len);
return (next_buff_pos <= packet_len) &&
(next_buff_pos <= BATADV_MAX_AGGREGATION_BYTES);
@@ -429,7 +435,7 @@ static void batadv_iv_ogm_send_to_if(str
/* adjust all flags and log packets */
while (batadv_iv_ogm_aggr_packet(buff_pos, forw_packet->packet_len,
- batadv_ogm_packet->tvlv_len)) {
+ batadv_ogm_packet)) {
/* we might have aggregated direct link packets with an
* ordinary base packet
*/
@@ -1745,7 +1751,7 @@ static int batadv_iv_ogm_receive(struct
/* unpack the aggregated packets and process them one by one */
while (batadv_iv_ogm_aggr_packet(ogm_offset, skb_headlen(skb),
- ogm_packet->tvlv_len)) {
+ ogm_packet)) {
batadv_iv_ogm_process(skb, ogm_offset, if_incoming);
ogm_offset += BATADV_OGM_HLEN;
