linux-kernel - Re: [syzbot] [can?] WARNING: refcount bug in j1939_session

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Message-ID: <tencent_1DA5E7E446CB52E4066CC9B82EC96EF38C06@qq.com>
Date: Wed,  7 Aug 2024 08:51:33 +0800
From: Edward Adam Davis <eadavis@...com>
To: syzbot+ad601904231505ad6617@...kaller.appspotmail.com
Cc: linux-kernel@...r.kernel.org,
	syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [can?] WARNING: refcount bug in j1939_session_put

because enabled CONFIG_DEBUG_NET, make refcount wrong dec?

#syz test: net-next 743ff02152bc

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index cf8f6ce06742..29c3ea5b6e93 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -1225,7 +1225,7 @@ static inline bool skb_unref(struct sk_buff *skb)
 {
 	if (unlikely(!skb))
 		return false;
-	if (!IS_ENABLED(CONFIG_DEBUG_NET) && likely(refcount_read(&skb->users) == 1))
+	if (likely(refcount_read(&skb->users) == 1))
 		smp_rmb();
 	else if (likely(!refcount_dec_and_test(&skb->users)))
 		return false;