[v4] qcow2 check: check some reserved bits and subcluster bitmaps

[PATCH v4 07/10] qcow2-refcount: check_refcounts_l2(): check reserved bits

Posted by Vladimir Sementsov-Ogievskiy 4 years, 4 months ago

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Tested-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Reviewed-by: Hanna Reitz <hreitz@redhat.com>
---
 block/qcow2.h          |  1 +
 block/qcow2-refcount.c | 12 +++++++++++-
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/block/qcow2.h b/block/qcow2.h
index c0e1e83796..b8b1093b61 100644
--- a/block/qcow2.h
+++ b/block/qcow2.h
@@ -587,6 +587,7 @@ typedef enum QCow2MetadataOverlap {
 
 #define L1E_OFFSET_MASK 0x00fffffffffffe00ULL
 #define L2E_OFFSET_MASK 0x00fffffffffffe00ULL
+#define L2E_STD_RESERVED_MASK 0x3f000000000001feULL
 
 #define REFT_OFFSET_MASK 0xfffffffffffffe00ULL
 
diff --git a/block/qcow2-refcount.c b/block/qcow2-refcount.c
index 9a5ae3cac4..5d57e677bc 100644
--- a/block/qcow2-refcount.c
+++ b/block/qcow2-refcount.c
@@ -1682,8 +1682,18 @@ static int check_refcounts_l2(BlockDriverState *bs, BdrvCheckResult *res,
         int csize;
         l2_entry = get_l2_entry(s, l2_table, i);
         l2_bitmap = get_l2_bitmap(s, l2_table, i);
+        QCow2ClusterType type = qcow2_get_cluster_type(bs, l2_entry);
 
-        switch (qcow2_get_cluster_type(bs, l2_entry)) {
+        if (type != QCOW2_CLUSTER_COMPRESSED) {
+            /* Check reserved bits of Standard Cluster Descriptor */
+            if (l2_entry & L2E_STD_RESERVED_MASK) {
+                fprintf(stderr, "ERROR found l2 entry with reserved bits set: "
+                        "%" PRIx64 "\n", l2_entry);
+                res->corruptions++;
+            }
+        }
+
+        switch (type) {
         case QCOW2_CLUSTER_COMPRESSED:
             /* Compressed clusters don't have QCOW_OFLAG_COPIED */
             if (l2_entry & QCOW_OFLAG_COPIED) {
-- 
2.29.2

Re: [PATCH v4 07/10] qcow2-refcount: check_refcounts_l2(): check reserved bits

Posted by Hanna Reitz 4 years, 4 months ago

On 14.09.21 14:24, Vladimir Sementsov-Ogievskiy wrote:
> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
> Reviewed-by: Eric Blake <eblake@redhat.com>
> Tested-by: Kirill Tkhai <ktkhai@virtuozzo.com>
> Reviewed-by: Hanna Reitz <hreitz@redhat.com>
> ---
>   block/qcow2.h          |  1 +
>   block/qcow2-refcount.c | 12 +++++++++++-
>   2 files changed, 12 insertions(+), 1 deletion(-)
>
> diff --git a/block/qcow2.h b/block/qcow2.h
> index c0e1e83796..b8b1093b61 100644
> --- a/block/qcow2.h
> +++ b/block/qcow2.h
> @@ -587,6 +587,7 @@ typedef enum QCow2MetadataOverlap {
>   
>   #define L1E_OFFSET_MASK 0x00fffffffffffe00ULL
>   #define L2E_OFFSET_MASK 0x00fffffffffffe00ULL
> +#define L2E_STD_RESERVED_MASK 0x3f000000000001feULL
>   
>   #define REFT_OFFSET_MASK 0xfffffffffffffe00ULL
>   
> diff --git a/block/qcow2-refcount.c b/block/qcow2-refcount.c
> index 9a5ae3cac4..5d57e677bc 100644
> --- a/block/qcow2-refcount.c
> +++ b/block/qcow2-refcount.c
> @@ -1682,8 +1682,18 @@ static int check_refcounts_l2(BlockDriverState *bs, BdrvCheckResult *res,
>           int csize;
>           l2_entry = get_l2_entry(s, l2_table, i);
>           l2_bitmap = get_l2_bitmap(s, l2_table, i);
> +        QCow2ClusterType type = qcow2_get_cluster_type(bs, l2_entry);

Hm, with l2_bitmap being declared next to l2_entry, this is now the 
patch that adds a declaration after a statement here.

(The possible resolutions seem to be the same, either move the 
declaration up to the function’s root block, or move l2_entry and 
l2_bitmap’s declarations here...)

(I don’t think we need a v5 for this, it should be fine if you tell me 
which way you prefer.)

Hanna

Re: [PATCH v4 07/10] qcow2-refcount: check_refcounts_l2(): check reserved bits

Posted by Vladimir Sementsov-Ogievskiy 4 years, 4 months ago

14.09.2021 20:15, Hanna Reitz wrote:
> On 14.09.21 14:24, Vladimir Sementsov-Ogievskiy wrote:
>> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
>> Reviewed-by: Eric Blake <eblake@redhat.com>
>> Tested-by: Kirill Tkhai <ktkhai@virtuozzo.com>
>> Reviewed-by: Hanna Reitz <hreitz@redhat.com>
>> ---
>>   block/qcow2.h          |  1 +
>>   block/qcow2-refcount.c | 12 +++++++++++-
>>   2 files changed, 12 insertions(+), 1 deletion(-)
>>
>> diff --git a/block/qcow2.h b/block/qcow2.h
>> index c0e1e83796..b8b1093b61 100644
>> --- a/block/qcow2.h
>> +++ b/block/qcow2.h
>> @@ -587,6 +587,7 @@ typedef enum QCow2MetadataOverlap {
>>   #define L1E_OFFSET_MASK 0x00fffffffffffe00ULL
>>   #define L2E_OFFSET_MASK 0x00fffffffffffe00ULL
>> +#define L2E_STD_RESERVED_MASK 0x3f000000000001feULL
>>   #define REFT_OFFSET_MASK 0xfffffffffffffe00ULL
>> diff --git a/block/qcow2-refcount.c b/block/qcow2-refcount.c
>> index 9a5ae3cac4..5d57e677bc 100644
>> --- a/block/qcow2-refcount.c
>> +++ b/block/qcow2-refcount.c
>> @@ -1682,8 +1682,18 @@ static int check_refcounts_l2(BlockDriverState *bs, BdrvCheckResult *res,
>>           int csize;
>>           l2_entry = get_l2_entry(s, l2_table, i);
>>           l2_bitmap = get_l2_bitmap(s, l2_table, i);
>> +        QCow2ClusterType type = qcow2_get_cluster_type(bs, l2_entry);

Oh :(

> 
> Hm, with l2_bitmap being declared next to l2_entry, this is now the patch that adds a declaration after a statement here.
> 
> (The possible resolutions seem to be the same, either move the declaration up to the function’s root block, or move l2_entry and l2_bitmap’s declarations here...)
> 
> (I don’t think we need a v5 for this, it should be fine if you tell me which way you prefer.)
> 

I'd keep type here:

QCow2ClusterType type;

l2_entry = ...
l2_bitmap = ...
type = qcow2_get_cluster_type(bs, l2_entry);


-- 
Best regards,
Vladimir