git: 4b61bd759c34 - stable/15 - mt76: ieee80211_is_first_frag() operates on the seq_ctrl field not on fc.

From: Bjoern A. Zeeb <bz_at_FreeBSD.org>
Date: Mon, 08 Dec 2025 15:44:24 UTC 
The branch stable/15 has been updated by bz:

URL: https://cgit.FreeBSD.org/src/commit/?id=4b61bd759c345c3fbfc0b18c9529a77124f48b82

commit 4b61bd759c345c3fbfc0b18c9529a77124f48b82
Author:     Bjoern A. Zeeb <bz@FreeBSD.org>
AuthorDate: 2025-11-29 00:51:36 +0000
Commit:     Bjoern A. Zeeb <bz@FreeBSD.org>
CommitDate: 2025-12-08 15:43:54 +0000

    mt76: ieee80211_is_first_frag() operates on the seq_ctrl field not on fc.
    
    Pass the correct field to ieee80211_is_first_frag(); otherwise the results
    may vary.
    
    Sponsored by:   The FreeBSD Foundation
    
    (cherry picked from commit c67fd35e58c6ee1e19877a7fe5998885683abedc)
---
 sys/contrib/dev/mediatek/mt76/mac80211.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/sys/contrib/dev/mediatek/mt76/mac80211.c b/sys/contrib/dev/mediatek/mt76/mac80211.c
index 927d8519104f..d2ace8870451 100644
--- a/sys/contrib/dev/mediatek/mt76/mac80211.c
+++ b/sys/contrib/dev/mediatek/mt76/mac80211.c
@@ -1340,7 +1340,7 @@ mt76_check_ccmp_pn(struct sk_buff *skb)
 		 * All further fragments will be validated by mac80211 only.
 		 */
 		if (ieee80211_is_frag(hdr) &&
-		    !ieee80211_is_first_frag(hdr->frame_control))
+		    !ieee80211_is_first_frag(hdr->seq_ctrl))
 			return;
 	}