[Qemu-devel] [PATCH 1/2] qcow2: add overlap check for bitmap directory

[Vladimir Sementsov-Ogievskiy]

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsement...@virtuozzo.com>
---
 block/qcow2.h          |  7 +++++--
 block/qcow2-refcount.c | 12 ++++++++++++
 block/qcow2.c          |  6 ++++++
 3 files changed, 23 insertions(+), 2 deletions(-)

diff --git a/block/qcow2.h b/block/qcow2.h
index 6f0ff15dd0..8f226a3609 100644
--- a/block/qcow2.h
+++ b/block/qcow2.h
@@ -98,6 +98,7 @@
 #define QCOW2_OPT_OVERLAP_SNAPSHOT_TABLE "overlap-check.snapshot-table"
 #define QCOW2_OPT_OVERLAP_INACTIVE_L1 "overlap-check.inactive-l1"
 #define QCOW2_OPT_OVERLAP_INACTIVE_L2 "overlap-check.inactive-l2"
+#define QCOW2_OPT_OVERLAP_BITMAP_DIRECTORY "overlap-check.bitmap-directory"
 #define QCOW2_OPT_CACHE_SIZE "cache-size"
 #define QCOW2_OPT_L2_CACHE_SIZE "l2-cache-size"
 #define QCOW2_OPT_REFCOUNT_CACHE_SIZE "refcount-cache-size"
@@ -406,8 +407,9 @@ typedef enum QCow2MetadataOverlap {
     QCOW2_OL_SNAPSHOT_TABLE_BITNR = 5,
     QCOW2_OL_INACTIVE_L1_BITNR    = 6,
     QCOW2_OL_INACTIVE_L2_BITNR    = 7,
+    QCOW2_OL_BITMAP_DIRECTORY_BITNR = 8,
 
-    QCOW2_OL_MAX_BITNR            = 8,
+    QCOW2_OL_MAX_BITNR              = 9,
 
     QCOW2_OL_NONE           = 0,
     QCOW2_OL_MAIN_HEADER    = (1 << QCOW2_OL_MAIN_HEADER_BITNR),
@@ -420,12 +422,13 @@ typedef enum QCow2MetadataOverlap {
     /* NOTE: Checking overlaps with inactive L2 tables will result in bdrv
      * reads. */
     QCOW2_OL_INACTIVE_L2    = (1 << QCOW2_OL_INACTIVE_L2_BITNR),
+    QCOW2_OL_BITMAP_DIRECTORY = (1 << QCOW2_OL_BITMAP_DIRECTORY_BITNR),
 } QCow2MetadataOverlap;
 
 /* Perform all overlap checks which can be done in constant time */
 #define QCOW2_OL_CONSTANT \
     (QCOW2_OL_MAIN_HEADER | QCOW2_OL_ACTIVE_L1 | QCOW2_OL_REFCOUNT_TABLE | \
-     QCOW2_OL_SNAPSHOT_TABLE)
+     QCOW2_OL_SNAPSHOT_TABLE | QCOW2_OL_BITMAP_DIRECTORY)
 
 /* Perform all overlap checks which don't require disk access */
 #define QCOW2_OL_CACHED \
diff --git a/block/qcow2-refcount.c b/block/qcow2-refcount.c
index 3de1ab51ba..a7a2703f26 100644
--- a/block/qcow2-refcount.c
+++ b/block/qcow2-refcount.c
@@ -2585,6 +2585,18 @@ int qcow2_check_metadata_overlap(BlockDriverState *bs, 
int ign, int64_t offset,
         }
     }
 
+    if ((chk & QCOW2_OL_BITMAP_DIRECTORY) &&
+        (s->autoclear_features & QCOW2_AUTOCLEAR_BITMAPS))
+    {
+        /* update_ext_header_and_dir_in_place firstly drop autoclear flag,
+         * so it will not fail */
+        if (overlaps_with(s->bitmap_directory_offset,
+                          s->bitmap_directory_size))
+        {
+            return QCOW2_OL_BITMAP_DIRECTORY;
+        }
+    }
+
     return 0;
 }
 
diff --git a/block/qcow2.c b/block/qcow2.c
index 1914a940e5..8278c0e124 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -655,6 +655,11 @@ static QemuOptsList qcow2_runtime_opts = {
             .help = "Check for unintended writes into an inactive L2 table",
         },
         {
+            .name = QCOW2_OPT_OVERLAP_BITMAP_DIRECTORY,
+            .type = QEMU_OPT_BOOL,
+            .help = "Check for unintended writes into the bitmap directory",
+        },
+        {
             .name = QCOW2_OPT_CACHE_SIZE,
             .type = QEMU_OPT_SIZE,
             .help = "Maximum combined metadata (L2 tables and refcount blocks) 
"
@@ -690,6 +695,7 @@ static const char 
*overlap_bool_option_names[QCOW2_OL_MAX_BITNR] = {
     [QCOW2_OL_SNAPSHOT_TABLE_BITNR] = QCOW2_OPT_OVERLAP_SNAPSHOT_TABLE,
     [QCOW2_OL_INACTIVE_L1_BITNR]    = QCOW2_OPT_OVERLAP_INACTIVE_L1,
     [QCOW2_OL_INACTIVE_L2_BITNR]    = QCOW2_OPT_OVERLAP_INACTIVE_L2,
+    [QCOW2_OL_BITMAP_DIRECTORY_BITNR] = QCOW2_OPT_OVERLAP_BITMAP_DIRECTORY,
 };
 
 static void cache_clean_timer_cb(void *opaque)
-- 
2.11.1