[PATCH 1/2] [PATCH] loop: prevent partial read

From: Dmitry Monakhov
Date: Mon Jan 24 2011 - 11:44:48 EST


If read was not fully successful we have to fail whole bio to
prevent information leak.

##Testcase_begin
dd if=/dev/zero of=./tmp 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@xxxxxxxxxx>
---
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 49e6a54..32e23f6 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -448,7 +448,8 @@ do_lo_receive(struct loop_device *lo,

if (retval < 0)
return retval;
-
+ if (retval != bvec->bv_len)
+ return -EIO;
return 0;
}

--
1.7.2.3

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