From: Hillf Danton <hdanton@sina.com>
To: syzbot <syzbot+e6382a2f53f5fc7453ac@syzkaller.appspotmail.com>
Cc: linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com
Subject: Re: [syzbot] [bluetooth?] KASAN: null-ptr-deref Read in l2cap_chan_hold_unless_zero
Date: Tue, 21 Jul 2026 12:26:33 +0800 [thread overview]
Message-ID: <20260721042635.643-1-hdanton@sina.com> (raw)
In-Reply-To: <6a5eb5ab.42649fcc.6186.008b.GAE@google.com>
> Date: Mon, 20 Jul 2026 16:56:27 -0700
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit: e22254e9ddd8 Merge tag 'xfs-fixes-7.2-rc4' of git://git.ke..
> git tree: upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=13d46789580000
> kernel config: https://syzkaller.appspot.com/x/.config?x=48ef5c5c0f192153
> dashboard link: https://syzkaller.appspot.com/bug?extid=e6382a2f53f5fc7453ac
> compiler: gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44
> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=17b434b9580000
> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=17d46789580000
#syz test
--- x/net/bluetooth/l2cap_sock.c
+++ y/net/bluetooth/l2cap_sock.c
@@ -1532,7 +1532,9 @@ static void l2cap_sock_cleanup_listen(st
struct l2cap_chan *chan;
lock_sock_nested(sk, L2CAP_NESTING_NORMAL);
- chan = l2cap_chan_hold_unless_zero(l2cap_pi(sk)->chan);
+ chan = l2cap_pi(sk)->chan;
+ if (chan)
+ chan = l2cap_chan_hold_unless_zero(l2cap_pi(sk)->chan);
release_sock(sk);
if (!chan) {
/* l2cap_conn_del() already tearing this child down */
--
next prev parent reply other threads:[~2026-07-21 4:29 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-07-20 23:56 syzbot
2026-07-21 4:26 ` Hillf Danton [this message]
2026-07-21 4:57 ` syzbot
2026-08-08 12:00 ` Forwarded: [PATCH] Bluetooth: L2CAP: fix race l2cap_sock_cleanup_listen() vs. put_chan syzbot
[not found] <95cf567c0e78b0ded9a555da052b4ea9b91aacce.1786190239.git.pav@iki.fi>
2026-08-08 12:30 ` [syzbot] [bluetooth?] KASAN: null-ptr-deref Read in l2cap_chan_hold_unless_zero syzbot
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