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

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Message-ID: <20250713073854.3864-1-hdanton@sina.com>
Date: Sun, 13 Jul 2025 15:38:53 +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/net/ipv4/ip_sockglue.c
+++ y/net/ipv4/ip_sockglue.c
@@ -1087,6 +1087,8 @@ int do_ip_setsockopt(struct sock *sk, in
 		err = ip_options_get(sock_net(sk), &opt, optval, optlen);
 		if (err)
 			break;
+		sockopt_release_sock(sk);
+		bh_lock_sock(sk);
 		old = rcu_dereference_protected(inet->inet_opt,
 						lockdep_sock_is_held(sk));
 		if (inet_test_bit(IS_ICSK, sk)) {
@@ -1109,6 +1111,8 @@ int do_ip_setsockopt(struct sock *sk, in
 		rcu_assign_pointer(inet->inet_opt, opt);
 		if (old)
 			kfree_rcu(old, rcu);
+		bh_unlock_sock(sk);
+		sockopt_lock_sock(sk);
 		break;
 	}
 	case IP_CHECKSUM:
--