linux-kernel - Re: [syzbot] [lsm?] [net?] WARNING in kvfree_call

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Message-ID: <20250714023645.3950-1-hdanton@sina.com>
Date: Mon, 14 Jul 2025 10:36:44 +0800
From: Hillf Danton <hdanton@...a.com>
To: syzbot <syzbot+40bf00346c3fe40f90f2@...kaller.appspotmail.com>
Cc: linux-kernel@...r.kernel.org,
	syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [lsm?] [net?] WARNING in kvfree_call_rcu

> Date: Tue, 08 Jul 2025 15:27:28 -0700	[thread overview]
> Hello,
> 
> syzbot found the following issue on:
> 
> HEAD commit:    7482bb149b9f Merge branch 'for-next/core' into for-kernelci
> git tree:       git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci
> console output: https://syzkaller.appspot.com/x/log.txt?x=130c528c580000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=3c06e3e2454512b3
> dashboard link: https://syzkaller.appspot.com/bug?extid=40bf00346c3fe40f90f2
> userspace arch: arm64
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1257428c580000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=15fe9582580000

#syz test

--- x/security/smack/smack_lsm.c
+++ y/security/smack/smack_lsm.c
@@ -2575,6 +2575,7 @@ static int smack_netlbl_add(struct sock
 	struct smack_known *skp = ssp->smk_out;
 	int rc;
 
+	sock_hold(sk);
 	local_bh_disable();
 	bh_lock_sock_nested(sk);
 
@@ -2591,6 +2592,7 @@ static int smack_netlbl_add(struct sock
 	}
 
 	bh_unlock_sock(sk);
+	sock_put(sk);
 	local_bh_enable();
 
 	return rc;
@@ -2612,10 +2614,12 @@ static void smack_netlbl_delete(struct s
 	if (ssp->smk_state != SMK_NETLBL_LABELED)
 		return;
 
+	sock_hold(sk);
 	local_bh_disable();
 	bh_lock_sock_nested(sk);
 	netlbl_sock_delattr(sk);
 	bh_unlock_sock(sk);
+	sock_put(sk);
 	local_bh_enable();
 	ssp->smk_state = SMK_NETLBL_UNLABELED;
 }
--