From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from r3-20.sinamail.sina.com.cn (r3-20.sinamail.sina.com.cn [202.108.3.20]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 159C918DB2A for ; Sat, 15 Nov 2025 00:45:09 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=202.108.3.20 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763167514; cv=none; b=GoOPiOT18ihThP3SFU6+/9ApxBLwbfy/yf0ty6JQV7YXXY4G0X/RHVnGFQXSzXA+Ya32abwUkRdf2mZ8UL7WvXGl0NBP3JS/JNaI27udWTapBdZ+EFAnO6gxNnhBFBgf3OZ0by8Qwm1HqC96xE3VrX3KKvX/M0MHJGurQ3a/iUc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763167514; c=relaxed/simple; bh=BVbKfvr20igbrnYRRoz8Ko0W2z7Cf/21BJsl7hq8eq0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Q54+BZV3YOD5t2g5Es2KambKgy/14d9n6abXDKHblklnnPNiScQD1mo5ITk4rp/22ODqb1Flu111zeGNLbKRwTeY54QU20TJBzy/sBan1QF/MZZnPG1H5qYRpy2E5YkGJ117vV3BdZtYVoY3ja3DHAZRe1tWeoW30KMC9SsioaE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=sina.com; spf=pass smtp.mailfrom=sina.com; dkim=pass (1024-bit key) header.d=sina.com header.i=@sina.com header.b=CrIHtf4R; arc=none smtp.client-ip=202.108.3.20 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=sina.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=sina.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=sina.com header.i=@sina.com header.b="CrIHtf4R" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sina.com; s=201208; t=1763167510; bh=J6Dz7AuMxS238uwLjJma0qGLlTM/mgQWGUiolWpaiYc=; h=From:Subject:Date:Message-ID; b=CrIHtf4RdPsRTPxE2+ZkC8t6ReLPChZcUfe28+EK71SNpgXd0/L1wahzkUz1L7Hs0 Tkyf+NuGU5GwaqiCTFTnAIWnU7ijb5IddIgKufkBvn1T50/ORx/3/eBdeZgS6IevOb FVv+5vpRFywcSEGI7xCC9dNnshUH6rZtpQ+6sGic= X-SMAIL-HELO: localhost.localdomain Received: from unknown (HELO localhost.localdomain)([114.249.57.85]) by sina.com (10.54.253.32) with ESMTP id 6917CD1100001F29; Sat, 15 Nov 2025 08:45:06 +0800 (CST) X-Sender: hdanton@sina.com X-Auth-ID: hdanton@sina.com Authentication-Results: sina.com; spf=none smtp.mailfrom=hdanton@sina.com; dkim=none header.i=none; dmarc=none action=none header.from=hdanton@sina.com X-SMAIL-MID: 9700734456674 X-SMAIL-UIID: 2CB888804CC947648224CC570AB40114-20251115-084506-1 From: Hillf Danton To: syzbot Cc: linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com Subject: Re: [syzbot] [bluetooth?] KASAN: slab-use-after-free Read in bt_accept_unlink Date: Sat, 15 Nov 2025 08:44:55 +0800 Message-ID: <20251115004456.9309-1-hdanton@sina.com> In-Reply-To: <6917b75a.050a0220.3565dc.0047.GAE@google.com> References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit > Date: Fri, 14 Nov 2025 15:12:26 -0800 > syzbot has found a reproducer for the following issue on: > > HEAD commit: db9030a787e3 Merge remote-tracking branch 'will/for-next/p.. > 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=13645c12580000 > kernel config: https://syzkaller.appspot.com/x/.config?x=fdc83aa8a8b9d1ae > dashboard link: https://syzkaller.appspot.com/bug?extid=a1595e656a83ea5b78eb > compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8 > userspace arch: arm64 > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=12cb37cd980000 #syz test --- x/net/bluetooth/af_bluetooth.c +++ y/net/bluetooth/af_bluetooth.c @@ -256,6 +256,8 @@ void bt_accept_unlink(struct sock *sk) { BT_DBG("sk %p state %d", sk, sk->sk_state); + if (bt_sk(sk)->parent == NULL) + return; list_del_init(&bt_sk(sk)->accept_q); sk_acceptq_removed(bt_sk(sk)->parent); bt_sk(sk)->parent = NULL; --- x/net/bluetooth/l2cap_sock.c +++ y/net/bluetooth/l2cap_sock.c @@ -1581,6 +1581,7 @@ static void l2cap_sock_teardown_cb(struc if (!sk) return; + sock_hold(sk); BT_DBG("chan %p state %s", chan, state_to_string(chan->state)); @@ -1613,8 +1614,14 @@ static void l2cap_sock_teardown_cb(struc sk->sk_err = err; if (parent) { + sock_hold(parent); + release_sock(sk); + lock_sock(parent); bt_accept_unlink(sk); + release_sock(parent); parent->sk_data_ready(parent); + sock_put(parent); + goto zap; } else { sk->sk_state_change(sk); } @@ -1623,9 +1630,10 @@ static void l2cap_sock_teardown_cb(struc } release_sock(sk); +zap: /* Only zap after cleanup to avoid use after free race */ sock_set_flag(sk, SOCK_ZAPPED); - + sock_put(sk); } static void l2cap_sock_state_change_cb(struct l2cap_chan *chan, int state, --