mtd: mtd_blkdevs: fix error path in blktrans_open

[Linux-MTD Mailing List]

Gitweb:     http://git.infradead.org/?p=mtd-2.6.git;a=commit;h=94735ec4044a6d318b83ad3c5794e931ed168d10
Commit:     94735ec4044a6d318b83ad3c5794e931ed168d10
Parent:     5c39c4c54c585e13a8d6b5a8f64af682e7c68091
Author:     Artem Bityutskiy <Artem.Bityutskiy at nokia.com>
AuthorDate: Mon Apr 18 07:50:37 2011 +0300
Committer:  David Woodhouse <David.Woodhouse at intel.com>
CommitDate: Wed May 25 01:53:45 2011 +0100

    mtd: mtd_blkdevs: fix error path in blktrans_open
    
    The 'blktrans_open()' does not handle possible '__get_mtd_device()' failures
    because it does not check the error code. Moreover, the 'dev->tr->open()'
    failures are not handled correctly because in this case the function just
    goes ahead and gets the mtd device, then returns an error. But Instead, it
    should _not_ try to get the mtd device, then it should put back the module
    and the kref.
    
    This patch fixes the issue. Note, I only compile-tested it. This patch was
    inspired by a bug report about a similar issue in 2.6.34 kernels
    sent by Mike Turner <admin at islandsoftware.co.uk> to the MTD mailing list:
    
    http://lists.infradead.org/pipermail/linux-mtd/2011-April/034980.html
    
    Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy at nokia.com>
    Signed-off-by: David Woodhouse <David.Woodhouse at intel.com>
---
 drivers/mtd/mtd_blkdevs.c |   24 +++++++++++++++++++++---
 1 files changed, 21 insertions(+), 3 deletions(-)

diff --git a/drivers/mtd/mtd_blkdevs.c b/drivers/mtd/mtd_blkdevs.c
index a534e1f..ca38569 100644
--- a/drivers/mtd/mtd_blkdevs.c
+++ b/drivers/mtd/mtd_blkdevs.c
@@ -221,15 +221,33 @@ static int blktrans_open(struct block_device *bdev, fmode_t mode)
 	kref_get(&dev->ref);
 	__module_get(dev->tr->owner);
 
-	if (dev->mtd) {
-		ret = dev->tr->open ? dev->tr->open(dev) : 0;
-		__get_mtd_device(dev->mtd);
+	if (!dev->mtd)
+		goto unlock;
+
+	if (dev->tr->open) {
+		ret = dev->tr->open(dev);
+		if (ret)
+			goto error_put;
 	}
 
+	ret = __get_mtd_device(dev->mtd);
+	if (ret)
+		goto error_release;
+
 unlock:
 	mutex_unlock(&dev->lock);
 	blktrans_dev_put(dev);
 	return ret;
+
+error_release:
+	if (dev->tr->release)
+		dev->tr->release(dev);
+error_put:
+	module_put(dev->tr->owner);
+	kref_put(&dev->ref, blktrans_dev_release);
+	mutex_unlock(&dev->lock);
+	blktrans_dev_put(dev);
+	return ret;
 }
 
 static int blktrans_release(struct gendisk *disk, fmode_t mode)