linux-kernel - Re: [syzbot] [bluetooth?] KASAN: null-ptr-deref Write in l2cap_sock_resume

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Message-ID: <20250708005930.2818-1-hdanton@sina.com>
Date: Tue,  8 Jul 2025 08:59:29 +0800
From: Hillf Danton <hdanton@...a.com>
To: syzbot <syzbot+e2df3a66f7d16fa6ec55@...kaller.appspotmail.com>
Cc: linux-kernel@...r.kernel.org,
	syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [bluetooth?] KASAN: null-ptr-deref Write in l2cap_sock_resume_cb (4)

> Date: Mon, 07 Jul 2025 11:32:29 -0700
> 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=1597828c580000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=3c06e3e2454512b3
> dashboard link: https://syzkaller.appspot.com/bug?extid=e2df3a66f7d16fa6ec55
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=17c4cbd4580000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=13d11f70580000

#syz test

--- x/net/bluetooth/l2cap_sock.c
+++ y/net/bluetooth/l2cap_sock.c
@@ -1703,6 +1703,9 @@ static void l2cap_sock_resume_cb(struct
 {
 	struct sock *sk = chan->data;
 
+	/* sock dead? */
+	if (!sk)
+		return;
 	if (test_and_clear_bit(FLAG_PENDING_SECURITY, &chan->flags)) {
 		sk->sk_state = BT_CONNECTED;
 		chan->state = BT_CONNECTED;
--