block: xen-blkfront: Fix possible NULL ptr dereference
In the blkif_release function the bdget_disk() call might returns
a NULL ptr which might be dereferenced on bdev->bd_openers checking
Signed-off-by: Felipe Pena <felipensp@gmail.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
[v2: Added WARN per Roger's suggestion]
diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
index 5f926de..c4a4c90 100644
--- a/drivers/block/xen-blkfront.c
+++ b/drivers/block/xen-blkfront.c
@@ -2011,6 +2011,10 @@
bdev = bdget_disk(disk, 0);
+ if (!bdev) {
+ WARN(1, "Block device %s yanked out from us!\n", disk->disk_name);
+ goto out_mutex;
+ }
if (bdev->bd_openers)
goto out;
@@ -2041,6 +2045,7 @@
out:
bdput(bdev);
+out_mutex:
mutex_unlock(&blkfront_mutex);
}