linux-kernel - [PATCH] omap2_mcspi.c: NULL pointer dereference

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Date:	Tue, 23 Feb 2010 14:36:03 -0500
From:	Scott Ellis <scott@...pnowtek.com>
To:	linux-kernel@...r.kernel.org
Cc:	David Brownell <dbrownell@...rs.sourceforge.net>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Tony Lindgren <tony@...mide.com>,
	Kevin Hilman <khilman@...prootsystems.com>,
	Aaro Koskinen <Aaro.Koskinen@...ia.com>,
	spi-devel-general@...ts.sourceforge.net,
	gumstix-users@...ts.sourceforge.net
Subject: [PATCH] omap2_mcspi.c: NULL pointer dereference

Check spi->controller_state before dereferencing.

Shows up NULL here when using spi_alloc_device()/spi_add_device() 
and spi_add_device() fails before spi_setup(). Calling spi_dev_put() 
on the leftover spi_device results in the error.

Signed-off-by: Scott Ellis <scott@...pnowtek.com>

 drivers/spi/omap2_mcspi.c |   10 ++++++----
 1 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/spi/omap2_mcspi.c b/drivers/spi/omap2_mcspi.c
index ba1a872..b1f82c1 100644
--- a/drivers/spi/omap2_mcspi.c
+++ b/drivers/spi/omap2_mcspi.c
@@ -751,11 +751,13 @@ static void omap2_mcspi_cleanup(struct spi_device *spi)
 	mcspi = spi_master_get_devdata(spi->master);
 	mcspi_dma = &mcspi->dma_channels[spi->chip_select];
 
-	/* Unlink controller state from context save list */
-	cs = spi->controller_state;
-	list_del(&cs->node);
+	if (spi->controller_state) {
+		/* Unlink controller state from context save list */
+		cs = spi->controller_state;
+		list_del(&cs->node);
 
-	kfree(spi->controller_state);
+		kfree(spi->controller_state);
+	}
 
 	if (mcspi_dma->dma_rx_channel != -1) {
 		omap_free_dma(mcspi_dma->dma_rx_channel);


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