FAILED: patch "[PATCH] batman-adv: avoid OGM aggregation when skb tailroom is" failed to apply to 6.1-stable tree

The patch below does not apply to the 6.1-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.1.y
git checkout FETCH_HEAD
git cherry-pick -x 0d4aef630be9d5f9c1227d07669c26c4383b5ad0
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2026032003-angrily-tranquil-eb2a@gregkh' --subject-prefix 'PATCH 6.1.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 0d4aef630be9d5f9c1227d07669c26c4383b5ad0 Mon Sep 17 00:00:00 2001
From: Yang Yang <[email protected]>
Date: Sat, 14 Mar 2026 07:11:27 +0000
Subject: [PATCH] batman-adv: avoid OGM aggregation when skb tailroom is
insufficient

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.

index b75c2228e69a..f28e9cbf8ad5 100644
@@ -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;
 

From: Yang Yang <[email protected]>

commit 0d4aef630be9d5f9c1227d07669c26c4383b5ad0 upstream.

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.

---
 net/batman-adv/bat_iv_ogm.c | 3 +++
 1 file changed, 3 insertions(+)

index 02e084b44053..0618f8efe88e 100644
@@ -465,6 +465,9 @@ batadv_iv_ogm_can_aggregate(const struct batadv_ogm_packet *new_bat_ogm_packet,
 	    !time_after_eq(aggregation_end_time, forw_packet->send_time))
 		return false;
 
+	if (skb_tailroom(forw_packet->skb) < packet_len)
+		return false;
+
 	if (aggregated_bytes > BATADV_MAX_AGGREGATION_BYTES)
 		return false;
 

2.47.3