Forwarded: [PATCH] WARNING in batadv_iv_ogm_process_per_outif

[syzbot <syzbot+a079f084653164a652d1@syzkaller.appspotmail.com>]

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Subject: [PATCH] WARNING in batadv_iv_ogm_process_per_outif
Author: jchuang26@m.fudan.edu.cn

#syz test: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master

Reported-by: syzbot+a079f084653164a652d1@syzkaller.appspotmail.com

diff --git a/net/batman-adv/bat_iv_ogm.c b/net/batman-adv/bat_iv_ogm.c
index 53fbdbbe8..24ea350cd 100644
--- a/net/batman-adv/bat_iv_ogm.c
+++ b/net/batman-adv/bat_iv_ogm.c
@@ -1410,9 +1410,13 @@ batadv_iv_ogm_update_seqnos(const struct ethhdr *ethhdr,
 		return BATADV_NO_DUP;
 
 	orig_ifinfo = batadv_orig_ifinfo_new(orig_node, if_outgoing);
-	if (WARN_ON(!orig_ifinfo)) {
+	if (!orig_ifinfo) {
+		/* The GFP_ATOMIC allocation inside batadv_orig_ifinfo_new()
+		 * may fail under memory pressure. That is not a kernel bug,
+		 * so don't WARN; just skip duplicate detection.
+		 */
 		batadv_orig_node_put(orig_node);
-		return 0;
+		return BATADV_NO_DUP;
 	}
 
 	spin_lock_bh(&orig_node->bat_iv.ogm_cnt_lock);