[PATCH] fix vulnerability of the release method of file operations inBlock layer SCSI generic driver

[Hillf Danton]

The computation context setup by previous opening the bsg file could
not survive following open/release operations upon the same file
object.

The vulnerability is fixed by deferring the cleanup operation until necessary.

Signed-off-by: Hillf Danton <dhillf@xxxxxxxxx>
---

--- a/block/bsg.c	2010-09-13 07:07:38.000000000 +0800
+++ b/block/bsg.c	2010-11-10 21:43:58.000000000 +0800
@@ -858,7 +858,8 @@ static int bsg_release(struct inode *ino
 {
 	struct bsg_device *bd = file->private_data;

-	file->private_data = NULL;
+	if (1 == atomic_read(&bd->ref_count))
+		file->private_data = NULL;
 	return bsg_put_device(bd);
 }
--
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