From patchwork Thu Jan 19 01:34:05 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sungwoo Kim X-Patchwork-Id: 13107280 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 63D14C38159 for ; Thu, 19 Jan 2023 01:37:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229646AbjASBhx (ORCPT ); Wed, 18 Jan 2023 20:37:53 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49192 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229899AbjASBfs (ORCPT ); Wed, 18 Jan 2023 20:35:48 -0500 Received: from mail-il1-f179.google.com (mail-il1-f179.google.com [209.85.166.179]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D631665AC; Wed, 18 Jan 2023 17:35:46 -0800 (PST) Received: by mail-il1-f179.google.com with SMTP id p12so487523ilq.10; Wed, 18 Jan 2023 17:35:46 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=tcLHpnRNh3ty5rv7JErXW5X+LMKRtJ6Ae8+AonT+Wt4=; b=0jLa0aGyVKMnt4/0y0IWTAk3bDxbSkFR0OThuSTTcKbqr3Vp/umF+56yBIgQT+wncE 9VcozD8zQMNki1kQCYc/uiQEVqjlzUiys0nVyCbaN+Wh02A2uUCcOmahXXdOz5N0Tkhl boCWyHypS7aGaspb39mZmvhXYQSIgYqOdd2yqoSgXPCBbVr+g3Adu9xhM6foy7j0oqwT gUeStPSpjBJxe31zJ5yMLtwuIjqfMCHYJ3j8Y6qxN+B0l62eZXkohMHOdpI+8sQCSE8D WvVMbfiYl9/bMPZRk4LXmORvhUatK9i0Xtmn7h/8pDVf+7pjzLOPJfqfjOKmUOUO1REX J/6Q== X-Gm-Message-State: AFqh2krR2gR//MhucOdkk6bRryC69FI7CZ3P4AvPK+0nkkA71TcYIPoM K4eirovp6NRuwyCASLUHyxg= X-Google-Smtp-Source: AMrXdXvxlTgKBAhWQR4LZca7F3Mn+uGGZnTz9tjG2PdmlP9Pq5eRuymaOtgjrbYGoVOO6TucK1UGTg== X-Received: by 2002:a05:6e02:2191:b0:30f:12c9:f767 with SMTP id j17-20020a056e02219100b0030f12c9f767mr9659967ila.11.1674092145973; Wed, 18 Jan 2023 17:35:45 -0800 (PST) Received: from noodle.cs.purdue.edu (switch-lwsn2133-z1r11.cs.purdue.edu. [128.10.127.250]) by smtp.googlemail.com with ESMTPSA id cs10-20020a056638470a00b0039d756fb908sm3547284jab.40.2023.01.18.17.35.43 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 18 Jan 2023 17:35:44 -0800 (PST) From: Sungwoo Kim Cc: daveti@purdue.edu, wuruoyu@me.com, benquike@gmail.com, Sungwoo Kim , Marcel Holtmann , Johan Hedberg , Luiz Augusto von Dentz , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , linux-bluetooth@vger.kernel.org (open list:BLUETOOTH SUBSYSTEM), netdev@vger.kernel.org (open list:NETWORKING [GENERAL]), linux-kernel@vger.kernel.org (open list) Subject: [PATCH] L2CAP: Fix null-ptr-deref in l2cap_sock_set_shutdown_cb Date: Wed, 18 Jan 2023 20:34:05 -0500 Message-Id: <20230119013405.3870506-1-iam@sung-woo.kim> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 To: unlisted-recipients:; (no To-header on input) Precedence: bulk List-ID: X-Mailing-List: linux-bluetooth@vger.kernel.org The L2CAP socket shutdown invokes l2cap_sock_destruct without a lock on conn->chan_lock, assigning NULL to chan->data *just before* the l2cap_disconnect_req thread that accesses to chan->data. This patch prevent it by adding a null check for a workaround, instead of fixing a lock. This bug is found by FuzzBT, a modified Syzkaller by Sungwoo Kim(me). Ruoyu Wu(wuruoyu@me.com) and Hui Peng(benquike@gmail.com) has helped the FuzzBT project. Signed-off-by: Sungwoo Kim --- net/bluetooth/l2cap_sock.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/net/bluetooth/l2cap_sock.c b/net/bluetooth/l2cap_sock.c index ca8f07f35..350c7afdf 100644 --- a/net/bluetooth/l2cap_sock.c +++ b/net/bluetooth/l2cap_sock.c @@ -1681,9 +1681,11 @@ static void l2cap_sock_set_shutdown_cb(struct l2cap_chan *chan) { struct sock *sk = chan->data; - lock_sock(sk); - sk->sk_shutdown = SHUTDOWN_MASK; - release_sock(sk); + if (!sk) { + lock_sock(sk); + sk->sk_shutdown = SHUTDOWN_MASK; + release_sock(sk); + } } static long l2cap_sock_get_sndtimeo_cb(struct l2cap_chan *chan)