From: Tejun Heo Date: Wed, 1 Jun 2011 06:27:41 +0000 (+0200) Subject: block: blkdev_get() should access ->bd_disk only after success X-Git-Tag: v2.6.39.2~76 X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=b7f788ce3f4ad895fe29cb225765c54f59a64d4d;p=karo-tx-linux.git block: blkdev_get() should access ->bd_disk only after success commit 4c49ff3fe128ca68dabd07537415c419ad7f82f9 upstream. d4dc210f69 (block: don't block events on excl write for non-optical devices) added dereferencing of bdev->bd_disk to test GENHD_FL_BLOCK_EVENTS_ON_EXCL_WRITE; however, bdev->bd_disk can be %NULL if open failed which can lead to an oops. Test the flag after testing open was successful, not before. Signed-off-by: Tejun Heo Reported-by: David Miller Tested-by: David Miller Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman --- diff --git a/fs/block_dev.c b/fs/block_dev.c index 1f2b19978333..1a2421f908f0 100644 --- a/fs/block_dev.c +++ b/fs/block_dev.c @@ -1272,8 +1272,8 @@ int blkdev_get(struct block_device *bdev, fmode_t mode, void *holder) * individual writeable reference is too fragile given the * way @mode is used in blkdev_get/put(). */ - if ((disk->flags & GENHD_FL_BLOCK_EVENTS_ON_EXCL_WRITE) && - !res && (mode & FMODE_WRITE) && !bdev->bd_write_holder) { + if (!res && (mode & FMODE_WRITE) && !bdev->bd_write_holder && + (disk->flags & GENHD_FL_BLOCK_EVENTS_ON_EXCL_WRITE)) { bdev->bd_write_holder = true; disk_block_events(disk); }