linux-kernel - [PATCH 3.19.y-ckt 67/86] spi: spidev: fix possible NULL dereference

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Message-Id: <1445981426-19727-68-git-send-email-kamal@canonical.com>
Date:	Tue, 27 Oct 2015 14:30:07 -0700
From:	Kamal Mostafa <kamal@...onical.com>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	kernel-team@...ts.ubuntu.com
Cc:	Sudip Mukherjee <sudip@...torindia.org>,
	Mark Brown <broonie@...nel.org>,
	Kamal Mostafa <kamal@...onical.com>
Subject: [PATCH 3.19.y-ckt 67/86] spi: spidev: fix possible NULL dereference

3.19.8-ckt9 -stable review patch.  If anyone has any objections, please let me know.

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

From: Sudip Mukherjee <sudipm.mukherjee@...il.com>

commit dd85ebf681ef0ee1fc985c353dd45e8b53b5dc1e upstream.

During the last close we are freeing spidev if spidev->spi is NULL, but
just before checking if spidev->spi is NULL we are dereferencing it.
Lets add a check there to avoid the NULL dereference.

Fixes: 9169051617df ("spi: spidev: Don't mangle max_speed_hz in underlying spi device")
Signed-off-by: Sudip Mukherjee <sudip@...torindia.org>
Reviewed-by: Jarkko Nikula <jarkko.nikula@...ux.intel.com>
Tested-by: Jarkko Nikula <jarkko.nikula@...ux.intel.com>
Signed-off-by: Mark Brown <broonie@...nel.org>
Signed-off-by: Kamal Mostafa <kamal@...onical.com>
---
 drivers/spi/spidev.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/spi/spidev.c b/drivers/spi/spidev.c
index 5c85435..e0bec45 100644
--- a/drivers/spi/spidev.c
+++ b/drivers/spi/spidev.c
@@ -579,7 +579,8 @@ static int spidev_release(struct inode *inode, struct file *filp)
 		kfree(spidev->rx_buffer);
 		spidev->rx_buffer = NULL;
 
-		spidev->speed_hz = spidev->spi->max_speed_hz;
+		if (spidev->spi)
+			spidev->speed_hz = spidev->spi->max_speed_hz;
 
 		/* ... after we unbound from the underlying device? */
 		spin_lock_irq(&spidev->spi_lock);
-- 
1.9.1

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