From mboxrd@z Thu Jan 1 00:00:00 1970 From: Geoff Lansberry Subject: [PATCH 3/3] nfc: trf7970a: Prevent repeated polling from crashing the kernel Date: Thu, 15 Dec 2016 17:30:44 -0500 Message-ID: <1481841044-4314-3-git-send-email-glansberry@gmail.com> References: <1481841044-4314-1-git-send-email-glansberry@gmail.com> Return-path: In-Reply-To: <1481841044-4314-1-git-send-email-glansberry@gmail.com> Sender: linux-kernel-owner@vger.kernel.org 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 List-Id: devicetree@vger.kernel.org From: Jaret Cantu Repeated polling attempts cause a NULL dereference error to occur. This is because the curent state of the trf7970a is reading but a request has been made to send a command. 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 b4c37ab..f96a321 100644 --- a/drivers/nfc/trf7970a.c +++ b/drivers/nfc/trf7970a.c @@ -1493,6 +1493,10 @@ 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