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Re: [Qemu-devel] [PATCH] qcow2 corruption: Fix alloc_cluster_link_l2
From: |
Christoph Hellwig |
Subject: |
Re: [Qemu-devel] [PATCH] qcow2 corruption: Fix alloc_cluster_link_l2 |
Date: |
Sun, 26 Apr 2009 15:24:44 +0200 |
User-agent: |
Mutt/1.3.28i |
On Wed, Apr 15, 2009 at 11:52:31AM +0200, 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.
>
> This bug is easy to trigger. The following script will create and destroy a
> qcow2 image (the header is gone after three loop iterations):
>
> #!/bin/bash
> 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
> quit
> EOF
> done
>
> 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);
Maybe it's time to make use of sparse's endianess annotations in qcow2
to prevent further problems like this one?