[Qemu-devel] [PATCH] qcow2: Correct endianness in overlap check

[Qemu-devel] [PATCH] qcow2: Correct endianness in overlap check

[Max Reitz]

If an inactive L1 table is loaded from disk, its entries are in big
endian and have to be converted to host byte order before using them.

Signed-off-by: Max Reitz <mreitz@redhat.com>
---
 block/qcow2-refcount.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/block/qcow2-refcount.c b/block/qcow2-refcount.c
index d2b7064..364eeba 100644
--- a/block/qcow2-refcount.c
+++ b/block/qcow2-refcount.c
@@ -1733,8 +1733,8 @@ int qcow2_check_metadata_overlap(BlockDriverState *bs, int chk, int64_t offset,
             }
 
             for (j = 0; j < l1_sz; j++) {
-                if ((l1[j] & L1E_OFFSET_MASK) &&
-                    overlaps_with(l1[j] & L1E_OFFSET_MASK, s->cluster_size)) {
+                uint64_t l2_ofs = be64_to_cpu(l1[j]) & L1E_OFFSET_MASK;
+                if (l2_ofs && overlaps_with(l2_ofs, s->cluster_size)) {
                     g_free(l1);
                     return QCOW2_OL_INACTIVE_L2;
                 }
-- 
1.8.3.1

Re: [Qemu-devel] [PATCH] qcow2: Correct endianness in overlap check

[Kevin Wolf]

Am 30.09.2013 um 08:59 hat Max Reitz geschrieben:
> If an inactive L1 table is loaded from disk, its entries are in big
> endian and have to be converted to host byte order before using them.
> 
> Signed-off-by: Max Reitz <mreitz@redhat.com>

Reviewed-by: Kevin Wolf <kwolf@redhat.com>

Sounds like there's yet a test case missing? (But it requires the
runtime options for enabling these checks, obviously)

Kevin

Re: [Qemu-devel] [PATCH] qcow2: Correct endianness in overlap check

[Max Reitz]

On 2013-09-30 10:06, Kevin Wolf wrote:
> Am 30.09.2013 um 08:59 hat Max Reitz geschrieben:
>> If an inactive L1 table is loaded from disk, its entries are in big
>> endian and have to be converted to host byte order before using them.
>>
>> Signed-off-by: Max Reitz <mreitz@redhat.com>
> Reviewed-by: Kevin Wolf <kwolf@redhat.com>
>
> Sounds like there's yet a test case missing? (But it requires the
> runtime options for enabling these checks, obviously)

Yes to both. For now, I just couldn't write such a test case.

Max

Re: [Qemu-devel] [PATCH] qcow2: Correct endianness in overlap check

[Stefan Hajnoczi]

On Mon, Sep 30, 2013 at 08:59:28AM +0200, Max Reitz wrote:
> If an inactive L1 table is loaded from disk, its entries are in big
> endian and have to be converted to host byte order before using them.
> 
> Signed-off-by: Max Reitz <mreitz@redhat.com>
> ---
>  block/qcow2-refcount.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)

Thanks, applied to my block tree:
https://github.com/stefanha/qemu/commits/block

Stefan