From patchwork Wed Jul 18 09:57:27 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Tetsuo Handa X-Patchwork-Id: 945642 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming-netdev@ozlabs.org Delivered-To: patchwork-incoming-netdev@ozlabs.org Authentication-Results: ozlabs.org; spf=none (mailfrom) smtp.mailfrom=vger.kernel.org (client-ip=209.132.180.67; helo=vger.kernel.org; envelope-from=netdev-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=none (p=none dis=none) header.from=I-love.SAKURA.ne.jp Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 41Vsyv3rG5z9s3R for ; Wed, 18 Jul 2018 19:57:59 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730911AbeGRKfD (ORCPT ); Wed, 18 Jul 2018 06:35:03 -0400 Received: from www262.sakura.ne.jp ([202.181.97.72]:24450 "EHLO www262.sakura.ne.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726121AbeGRKfC (ORCPT ); Wed, 18 Jul 2018 06:35:02 -0400 Received: from fsav301.sakura.ne.jp (fsav301.sakura.ne.jp [153.120.85.132]) by www262.sakura.ne.jp (8.15.2/8.15.2) with ESMTP id w6I9viLG029499; Wed, 18 Jul 2018 18:57:44 +0900 (JST) (envelope-from penguin-kernel@I-love.SAKURA.ne.jp) Received: from www262.sakura.ne.jp (202.181.97.72) by fsav301.sakura.ne.jp (F-Secure/fsigk_smtp/530/fsav301.sakura.ne.jp); Wed, 18 Jul 2018 18:57:44 +0900 (JST) X-Virus-Status: clean(F-Secure/fsigk_smtp/530/fsav301.sakura.ne.jp) Received: from ccsecurity.localdomain (softbank126074194044.bbtec.net [126.74.194.44]) (authenticated bits=0) by www262.sakura.ne.jp (8.15.2/8.15.2) with ESMTPSA id w6I9vexp029458 (version=TLSv1.2 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NO); Wed, 18 Jul 2018 18:57:44 +0900 (JST) (envelope-from penguin-kernel@I-love.SAKURA.ne.jp) From: Tetsuo Handa To: Samuel Ortiz Cc: "David S. Miller" , linux-wireless@vger.kernel.org, netdev@vger.kernel.org, Tetsuo Handa , syzbot Subject: [PATCH] net/nfc: Avoid stalls when nfc_alloc_send_skb() returned NULL. Date: Wed, 18 Jul 2018 18:57:27 +0900 Message-Id: <1531907847-3500-1-git-send-email-penguin-kernel@I-love.SAKURA.ne.jp> X-Mailer: git-send-email 1.8.3.1 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org syzbot is reporting stalls at nfc_llcp_send_ui_frame() [1]. This is because nfc_llcp_send_ui_frame() is retrying the loop without any delay when nonblocking nfc_alloc_send_skb() returned NULL. Since there is no need to use MSG_DONTWAIT if we retry until sock_alloc_send_pskb() succeeds, let's use blocking call. Also, in case an unexpected error occurred, let's break the loop if blocking nfc_alloc_send_skb() failed. [1] https://syzkaller.appspot.com/bug?id=4a131cc571c3733e0eff6bc673f4e36ae48f19c6 Signed-off-by: Tetsuo Handa Reported-by: syzbot --- net/nfc/llcp_commands.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/net/nfc/llcp_commands.c b/net/nfc/llcp_commands.c index 2ceefa1..6a196e4 100644 --- a/net/nfc/llcp_commands.c +++ b/net/nfc/llcp_commands.c @@ -752,11 +752,14 @@ int nfc_llcp_send_ui_frame(struct nfc_llcp_sock *sock, u8 ssap, u8 dsap, pr_debug("Fragment %zd bytes remaining %zd", frag_len, remaining_len); - pdu = nfc_alloc_send_skb(sock->dev, &sock->sk, MSG_DONTWAIT, + pdu = nfc_alloc_send_skb(sock->dev, &sock->sk, 0, frag_len + LLCP_HEADER_SIZE, &err); if (pdu == NULL) { - pr_err("Could not allocate PDU\n"); - continue; + pr_err("Could not allocate PDU (error=%d)\n", err); + len -= remaining_len; + if (len == 0) + len = err; + break; } pdu = llcp_add_header(pdu, dsap, ssap, LLCP_PDU_UI);