linux-kernel - [PATCH 4.16 138/161] media: lgdt3306a: Fix a double kfree on i2c device remove

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Date:   Thu, 24 May 2018 11:39:23 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Brad Love <brad@...tdimension.cc>,
        Mauro Carvalho Chehab <mchehab@...pensource.com>,
        Sasha Levin <alexander.levin@...rosoft.com>
Subject: [PATCH 4.16 138/161] media: lgdt3306a: Fix a double kfree on i2c device remove

4.16-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Brad Love <brad@...tdimension.cc>

[ Upstream commit 94448e21cf08b10f7dc7acdaca387594370396b0 ]

Both lgdt33606a_release and lgdt3306a_remove kfree state, but _release is
called first, then _remove operates on states members before kfree'ing it.
This can lead to random oops/GPF/etc on USB disconnect.

Signed-off-by: Brad Love <brad@...tdimension.cc>
Signed-off-by: Mauro Carvalho Chehab <mchehab@...pensource.com>
Signed-off-by: Sasha Levin <alexander.levin@...rosoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/media/dvb-frontends/lgdt3306a.c |    8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

--- a/drivers/media/dvb-frontends/lgdt3306a.c
+++ b/drivers/media/dvb-frontends/lgdt3306a.c
@@ -1768,7 +1768,13 @@ static void lgdt3306a_release(struct dvb
 	struct lgdt3306a_state *state = fe->demodulator_priv;
 
 	dbg_info("\n");
-	kfree(state);
+
+	/*
+	 * If state->muxc is not NULL, then we are an i2c device
+	 * and lgdt3306a_remove will clean up state
+	 */
+	if (!state->muxc)
+		kfree(state);
 }
 
 static const struct dvb_frontend_ops lgdt3306a_ops;