Return-path: Received: from mail-qt0-f178.google.com ([209.85.216.178]:33340 "EHLO mail-qt0-f178.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756954AbcLTQQp (ORCPT ); Tue, 20 Dec 2016 11:16:45 -0500 Received: by mail-qt0-f178.google.com with SMTP id p16so178787273qta.0 for ; Tue, 20 Dec 2016 08:16:44 -0800 (PST) From: Geoff Lansberry To: linux-wireless@vger.kernel.org Cc: lauro.venancio@openbossa.org, aloisio.almeida@openbossa.org, sameo@linux.intel.com, robh+dt@kernel.org, mark.rutland@arm.com, netdev@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, mgreer@animalcreek.com, justin@kuvee.com, Jaret Cantu , Geoff Lansberry Subject: [PATCH 3/3] nfc: trf7970a: Prevent repeated polling from crashing the kernel Date: Tue, 20 Dec 2016 11:16:32 -0500 Message-Id: <1482250592-4268-3-git-send-email-glansberry@gmail.com> (sfid-20161220_171802_321796_A12D9CD6) In-Reply-To: <1482250592-4268-1-git-send-email-glansberry@gmail.com> References: <1482250592-4268-1-git-send-email-glansberry@gmail.com> Sender: linux-wireless-owner@vger.kernel.org List-ID: From: Jaret Cantu Repeated polling attempts cause a NULL dereference error to occur. This is because the state of the trf7970a is currently reading but another request has been made to send a command before it has finished. The solution is to properly kill the waiting reading (workqueue) before failing on the send. --- drivers/nfc/trf7970a.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/drivers/nfc/trf7970a.c b/drivers/nfc/trf7970a.c index 8a88195..5916737 100644 --- a/drivers/nfc/trf7970a.c +++ b/drivers/nfc/trf7970a.c @@ -1496,6 +1496,10 @@ static int trf7970a_send_cmd(struct nfc_digital_dev *ddev, (trf->state != TRF7970A_ST_IDLE_RX_BLOCKED)) { dev_err(trf->dev, "%s - Bogus state: %d\n", __func__, trf->state); + if (trf->state == TRF7970A_ST_WAIT_FOR_RX_DATA || + trf->state == TRF7970A_ST_WAIT_FOR_RX_DATA_CONT) + trf->ignore_timeout = + !cancel_delayed_work(&trf->timeout_work); ret = -EIO; goto out_err; } -- Signed-off-by: Geoff Lansberry