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[Qemu-devel] Re: [PATCH] qcow2 corruption: Fix alloc_cluster_link_l2

From: Consul
Subject: [Qemu-devel] Re: [PATCH] qcow2 corruption: Fix alloc_cluster_link_l2
Date: Wed, 15 Apr 2009 08:28:56 -0700
User-agent: Thunderbird (Windows/20090302)

Kevin Wolf wrote:
This patch fixes a qcow2 corruption bug introduced in SVN Rev 5861. L2 tables
are big endian, so entries must be converted before being passed to functions.

Excellent! I think it is this bug who bit me more than once.
Acked-by: Alex Ivanov <address@hidden>

This bug is easy to trigger. The following script will create and destroy a
qcow2 image (the header is gone after three loop iterations):

    qemu-img create -f qcow2 test.qcow 1M
    for i in $(seq 1 10); do
    qemu-system-x86_64 -hda test.qcow -monitor stdio > /dev/null 2>&1 <<EOF
    savevm test-$i

Signed-off-by: Kevin Wolf <address@hidden>
 block-qcow2.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/block-qcow2.c b/block-qcow2.c
index da8fb42..985214f 100644
--- a/block-qcow2.c
+++ b/block-qcow2.c
@@ -1007,7 +1007,7 @@ static int alloc_cluster_link_l2(BlockDriverState *bs, 
uint64_t cluster_offset,
         goto err;
for (i = 0; i < j; i++)
-        free_any_clusters(bs, old_cluster[i], 1);
+        free_any_clusters(bs, be64_to_cpu(old_cluster[i]), 1);
ret = 0;

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