From: Dmitry Monakhov <dmonakhov@openvz.org>
Date: Tue, 8 Nov 2011 00:20:06 +0000 (+1100)
Subject: loop: prevent information leak after failed read
X-Git-Tag: next-20111109~1^2~53
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=72fd33aab201054406d4c9354214672681c0c109;p=karo-tx-linux.git

loop: prevent information leak after failed read

If read was not fully successful we have to fail whole bio to prevent
information leak of old pages

##Testcase_begin
dd if=/dev/zero of=./file bs=1M count=1
losetup /dev/loop0 ./file -o 4096
truncate -s 0 ./file
# OOps loop offset is now beyond i_size, so read will silently fail.
# So bio's pages would not be cleared, may which result in information leak.
hexdump -C /dev/loop0
##testcase_end

Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index 3d806820280e..0d567397c254 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -372,7 +372,8 @@ do_lo_receive(struct loop_device *lo,
 
 	if (retval < 0)
 		return retval;
-
+	if (retval != bvec->bv_len)
+		return -EIO;
 	return 0;
 }