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From: Geoff Lansberry <geoff@kuvee.com>
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 <jaret.cantu@timesys.com>,
	Geoff Lansberry <geoff@kuvee.com>
Subject: [PATCH 3/3] nfc: trf7970a: Prevent repeated polling from crashing the kernel
Date: Thu, 15 Dec 2016 17:30:44 -0500	[thread overview]
Message-ID: <1481841044-4314-3-git-send-email-glansberry@gmail.com> (raw)
In-Reply-To: <1481841044-4314-1-git-send-email-glansberry@gmail.com>

From: Jaret Cantu <jaret.cantu@timesys.com>

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 <geoff@kuvee.com>

  parent reply	other threads:[~2016-12-15 22:31 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-12-15 22:30 [PATCH 1/3] NFC: trf7970a: add device tree option for 27MHz clock Geoff Lansberry
2016-12-15 22:30 ` [PATCH 2/3] NFC: trf7970a: Add device tree option of 1.8 Volt IO voltage Geoff Lansberry
2016-12-16  1:13   ` Mark Greer
2016-12-19 22:35   ` Rob Herring
2016-12-20 16:13     ` Geoff Lansberry
2016-12-21  2:07       ` Mark Greer
2016-12-15 22:30 ` Geoff Lansberry [this message]
2016-12-16  1:18   ` [PATCH 3/3] nfc: trf7970a: Prevent repeated polling from crashing the kernel Mark Greer
2016-12-16  1:06 ` [PATCH 1/3] NFC: trf7970a: add device tree option for 27MHz clock Mark Greer
2016-12-19 22:31 ` Rob Herring
2016-12-19 23:23   ` Geoff Lansberry
2016-12-22 18:48     ` Rob Herring
2016-12-20 16:10 Geoff Lansberry
2016-12-20 16:10 ` [PATCH 3/3] nfc: trf7970a: Prevent repeated polling from crashing the kernel Geoff Lansberry
2016-12-20 16:16 [PATCH 1/3] NFC: trf7970a: add device tree option for 27MHz clock Geoff Lansberry
2016-12-20 16:16 ` [PATCH 3/3] nfc: trf7970a: Prevent repeated polling from crashing the kernel Geoff Lansberry
2016-12-20 18:59   ` Mark Greer

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