bitmap: Enforce maximum bitmap name length

We document that for qcow2 persistent bitmaps, the name cannot exceed
1023 bytes.  It is inconsistent if transient bitmaps do not have to
abide by the same limit, and it is unlikely that any existing client
even cares about using bitmap names this long.  It's time to codify
that ALL bitmaps managed by qemu (whether persistent in qcow2 or not)
have a documented maximum length.

Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <20191114024635.11363-3-eblake@redhat.com>
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>

diff --git a/block/dirty-bitmap.c b/block/dirty-bitmap.c
index 4bbb251b2c9c20033369fb23d74d89939363c0ae..7039e8252009bc85a5de111cfb75c3cb92278a3c 100644 (file)
--- a/block/dirty-bitmap.c
+++ b/block/dirty-bitmap.c
@@ -104,9 +104,15 @@ BdrvDirtyBitmap *bdrv_create_dirty_bitmap(BlockDriverState *bs,
 
     assert(is_power_of_2(granularity) && granularity >= BDRV_SECTOR_SIZE);
 
-    if (name && bdrv_find_dirty_bitmap(bs, name)) {
-        error_setg(errp, "Bitmap already exists: %s", name);
-        return NULL;
+    if (name) {
+        if (bdrv_find_dirty_bitmap(bs, name)) {
+            error_setg(errp, "Bitmap already exists: %s", name);
+            return NULL;
+        }
+        if (strlen(name) > BDRV_BITMAP_MAX_NAME_SIZE) {
+            error_setg(errp, "Bitmap name too long: %s", name);
+            return NULL;
+        }
     }
     bitmap_size = bdrv_getlength(bs);
     if (bitmap_size < 0) {

diff --git a/block/qcow2-bitmap.c b/block/qcow2-bitmap.c
index ef9ef628a0d049571c74371e51a206283402a02d..809bbc5d20c88ca69d5ca7a3553feae38f135fe5 100644 (file)
--- a/block/qcow2-bitmap.c
+++ b/block/qcow2-bitmap.c
@@ -42,6 +42,8 @@
 #define BME_MIN_GRANULARITY_BITS 9
 #define BME_MAX_NAME_SIZE 1023
 
+QEMU_BUILD_BUG_ON(BME_MAX_NAME_SIZE != BDRV_BITMAP_MAX_NAME_SIZE);
+
 #if BME_MAX_TABLE_SIZE * 8ULL > INT_MAX
 #error In the code bitmap table physical size assumed to fit into int
 #endif

diff --git a/include/block/dirty-bitmap.h b/include/block/dirty-bitmap.h
index 958e7474fb516f072f8339ec1f1f91ead0fa376f..e2b20ecab9a341a1ff1da9b82e0f8cd7c30a091c 100644 (file)
--- a/include/block/dirty-bitmap.h
+++ b/include/block/dirty-bitmap.h
@@ -14,6 +14,8 @@ typedef enum BitmapCheckFlags {
                              BDRV_BITMAP_INCONSISTENT)
 #define BDRV_BITMAP_ALLOW_RO (BDRV_BITMAP_BUSY | BDRV_BITMAP_INCONSISTENT)
 
+#define BDRV_BITMAP_MAX_NAME_SIZE 1023
+
 BdrvDirtyBitmap *bdrv_create_dirty_bitmap(BlockDriverState *bs,
                                           uint32_t granularity,
                                           const char *name,

diff --git a/qapi/block-core.json b/qapi/block-core.json
index aa97ee2641127b75868997497c443810c2390e44..0cf68fea1450e6cb739863d2367ce03ee95d58a5 100644 (file)
--- a/qapi/block-core.json
+++ b/qapi/block-core.json
@@ -2042,7 +2042,7 @@
 #
 # @node: name of device/node which the bitmap is tracking
 #
-# @name: name of the dirty bitmap
+# @name: name of the dirty bitmap (must be less than 1024 bytes)
 #
 # @granularity: the bitmap granularity, default is 64k for
 #               block-dirty-bitmap-add