From mboxrd@z Thu Jan 1 00:00:00 1970 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 64D57C433F5 for ; Tue, 26 Apr 2022 08:40:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1345533AbiDZIn2 (ORCPT ); Tue, 26 Apr 2022 04:43:28 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60516 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1345696AbiDZIfA (ORCPT ); Tue, 26 Apr 2022 04:35:00 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E84B87B554; Tue, 26 Apr 2022 01:28:07 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 79C6D61861; Tue, 26 Apr 2022 08:28:07 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 84A22C385A0; Tue, 26 Apr 2022 08:28:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1650961686; bh=6Gyh6pHcC1BHzZyxNOnQ480YdvWAvjN2LeI3P34j8Eg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Nnn6T8q67xeZTlB4Crvan+aToqc850cx/okUdk+FAsYtZ1oosaEV0zvb+RCzqgIZ9 3SIbEaO/jZQ3e/Q520enWHc8KQwvffygxOlLPcQIF2hQ0cg0LoisT6U4NJD2ljO78u iZKUIS0Q6DX0+oDQE0SvnZ5vjp+NmHpej7jiFOH8= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Greg Kroah-Hartman , Duoming Zhou , "David S. Miller" , Ovidiu Panait Subject: [PATCH 4.19 50/53] ax25: fix NPD bug in ax25_disconnect Date: Tue, 26 Apr 2022 10:21:30 +0200 Message-Id: <20220426081737.119880374@linuxfoundation.org> X-Mailer: git-send-email 2.36.0 In-Reply-To: <20220426081735.651926456@linuxfoundation.org> References: <20220426081735.651926456@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Duoming Zhou commit 7ec02f5ac8a5be5a3f20611731243dc5e1d9ba10 upstream. The ax25_disconnect() in ax25_kill_by_device() is not protected by any locks, thus there is a race condition between ax25_disconnect() and ax25_destroy_socket(). when ax25->sk is assigned as NULL by ax25_destroy_socket(), a NULL pointer dereference bug will occur if site (1) or (2) dereferences ax25->sk. ax25_kill_by_device() | ax25_release() ax25_disconnect() | ax25_destroy_socket() ... | if(ax25->sk != NULL) | ... ... | ax25->sk = NULL; bh_lock_sock(ax25->sk); //(1) | ... ... | bh_unlock_sock(ax25->sk); //(2)| This patch moves ax25_disconnect() into lock_sock(), which can synchronize with ax25_destroy_socket() in ax25_release(). Fail log: =============================================================== BUG: kernel NULL pointer dereference, address: 0000000000000088 ... RIP: 0010:_raw_spin_lock+0x7e/0xd0 ... Call Trace: ax25_disconnect+0xf6/0x220 ax25_device_event+0x187/0x250 raw_notifier_call_chain+0x5e/0x70 dev_close_many+0x17d/0x230 rollback_registered_many+0x1f1/0x950 unregister_netdevice_queue+0x133/0x200 unregister_netdev+0x13/0x20 ... Signed-off-by: Duoming Zhou Signed-off-by: David S. Miller [OP: backport to 4.19: adjust context] Signed-off-by: Ovidiu Panait Signed-off-by: Greg Kroah-Hartman --- net/ax25/af_ax25.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/net/ax25/af_ax25.c +++ b/net/ax25/af_ax25.c @@ -105,8 +105,8 @@ again: dev_put(ax25_dev->dev); ax25_dev_put(ax25_dev); } - release_sock(sk); ax25_disconnect(s, ENETUNREACH); + release_sock(sk); spin_lock_bh(&ax25_list_lock); sock_put(sk); /* The entry could have been deleted from the