linux-kernel - [PATCH 1/2] loop: prevent information leak after failed read

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Message-Id: <1316775689-22695-1-git-send-email-dmonakhov@openvz.org>
Date:	Fri, 23 Sep 2011 15:01:28 +0400
From:	Dmitry Monakhov <dmonakhov@...nvz.org>
To:	linux-kernel@...r.kernel.org
Cc:	jaxboe@...ionio.com, akpm@...ux-foundation.org,
	Dmitry Monakhov <dmonakhov@...nvz.org>
Subject: [PATCH 1/2] 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@...nvz.org>
---
 drivers/block/loop.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index 4720c7a..0dcc7bf 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -447,7 +447,8 @@ do_lo_receive(struct loop_device *lo,
 
 	if (retval < 0)
 		return retval;
-
+	if (retval != bvec->bv_len)
+		return -EIO;
 	return 0;
 }
 
-- 
1.7.1

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