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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Mario Forner <m.forner@be4energy.com>,
        Alexandre Belloni <alexandre.belloni@bootlin.com>,
        Ludovic Desroches <ludovic.desroches@microchip.com>,
        Richard Genoud <richard.genoud@gmail.com>,
        Vinod Koul <vkoul@kernel.org>
Subject: [PATCH 4.19 122/139] dmaengine: at_hdmac: fix memory leak in at_dma_xlate()
Date:   Tue,  4 Dec 2018 11:50:03 +0100
Message-Id: <20181204103655.714571582@linuxfoundation.org>
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4.19-stable review patch.  If anyone has any objections, please let me know.

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

From: Richard Genoud <richard.genoud@gmail.com>

commit 98f5f932254b88ce828bc8e4d1642d14e5854caa upstream.

The leak was found when opening/closing a serial port a great number of
time, increasing kmalloc-32 in slabinfo.

Each time the port was opened, dma_request_slave_channel() was called.
Then, in at_dma_xlate(), atslave was allocated with devm_kzalloc() and
never freed. (Well, it was free at module unload, but that's not what we
want).
So, here, kzalloc is more suited for the job since it has to be freed in
atc_free_chan_resources().

Cc: stable@vger.kernel.org
Fixes: bbe89c8e3d59 ("at_hdmac: move to generic DMA binding")
Reported-by: Mario Forner <m.forner@be4energy.com>
Suggested-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Acked-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Acked-by: Ludovic Desroches <ludovic.desroches@microchip.com>
Signed-off-by: Richard Genoud <richard.genoud@gmail.com>
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/dma/at_hdmac.c |    8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

--- a/drivers/dma/at_hdmac.c
+++ b/drivers/dma/at_hdmac.c
@@ -1641,6 +1641,12 @@ static void atc_free_chan_resources(stru
 	atchan->descs_allocated = 0;
 	atchan->status = 0;
 
+	/*
+	 * Free atslave allocated in at_dma_xlate()
+	 */
+	kfree(chan->private);
+	chan->private = NULL;
+
 	dev_vdbg(chan2dev(chan), "free_chan_resources: done\n");
 }
 
@@ -1675,7 +1681,7 @@ static struct dma_chan *at_dma_xlate(str
 	dma_cap_zero(mask);
 	dma_cap_set(DMA_SLAVE, mask);
 
-	atslave = devm_kzalloc(&dmac_pdev->dev, sizeof(*atslave), GFP_KERNEL);
+	atslave = kzalloc(sizeof(*atslave), GFP_KERNEL);
 	if (!atslave)
 		return NULL;