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[108.20.204.117]) by smtp.googlemail.com with ESMTPSA id o190sm17141995qke.5.2016.12.21.20.19.23 (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Wed, 21 Dec 2016 20:19:23 -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 v3 3/3] nfc: trf7970a: Prevent repeated polling from crashing the kernel Date: Wed, 21 Dec 2016 23:18:34 -0500 Message-Id: <1482380314-16440-3-git-send-email-geoff@kuvee.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1482380314-16440-1-git-send-email-geoff@kuvee.com> References: <1482380314-16440-1-git-send-email-geoff@kuvee.com> Sender: linux-wireless-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-wireless@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP 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. Signed-off-by: Geoff Lansberry --- drivers/nfc/trf7970a.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/drivers/nfc/trf7970a.c b/drivers/nfc/trf7970a.c index e3c72c6..ba5f9b8 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; }