[PATCH net 1/1] batman-adv: avoid OGM aggregation when skb tailroom is insufficient

[Simon Wunderlich <sw@simonwunderlich.de>]

From: Yang Yang <n05ec@lzu.edu.cn>

When OGM aggregation state is toggled at runtime, an existing forwarded
packet may have been allocated with only packet_len bytes, while a later
packet can still be selected for aggregation. Appending in this case can
hit skb_put overflow conditions.

Reject aggregation when the target skb tailroom cannot accommodate the new
packet. The caller then falls back to creating a new forward packet
instead of appending.

Fixes: c6c8fea29769 ("net: Add batman-adv meshing protocol")
Cc: stable@vger.kernel.org
Reported-by: Yifan Wu <yifanwucs@gmail.com>
Reported-by: Juefei Pu <tomapufckgml@gmail.com>
Signed-off-by: Yuan Tan <tanyuan98@outlook.com>
Signed-off-by: Xin Liu <bird@lzu.edu.cn>
Signed-off-by: Ao Zhou <n05ec@lzu.edu.cn>
Signed-off-by: Yang Yang <n05ec@lzu.edu.cn>
Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>
---
 net/batman-adv/bat_iv_ogm.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/net/batman-adv/bat_iv_ogm.c b/net/batman-adv/bat_iv_ogm.c
index b75c2228e69a6..f28e9cbf8ad5f 100644
--- a/net/batman-adv/bat_iv_ogm.c
+++ b/net/batman-adv/bat_iv_ogm.c
@@ -473,6 +473,9 @@ batadv_iv_ogm_can_aggregate(const struct batadv_ogm_packet *new_bat_ogm_packet,
 	if (aggregated_bytes > max_bytes)
 		return false;
 
+	if (skb_tailroom(forw_packet->skb) < packet_len)
+		return false;
+
 	if (packet_num >= BATADV_MAX_AGGREGATION_PACKETS)
 		return false;
 
-- 
2.47.3