If we were to allow resizes, the length check that happens when we load
bitmap headers from disk when we read or store bitmaps would begin to
fail:
Imagine the circumstance where we've resized bitmaps in memory, but they still
have the old values on-disk. The lengths will no longer match bdrv_getlength,
so we must allow this check to be skipped when flushing bitmaps to disk.
Limit this to when we are about to overwrite the headers: we will verify the
outgoing headers, but we will skip verifying the known stale headers.
Signed-off-by: John Snow <js...@redhat.com>
---
block/qcow2-bitmap.c | 34 +++++++++++++++++++++-------------
1 file changed, 21 insertions(+), 13 deletions(-)
diff --git a/block/qcow2-bitmap.c b/block/qcow2-bitmap.c
index c3b210ede1..d02730004a 100644
--- a/block/qcow2-bitmap.c
+++ b/block/qcow2-bitmap.c
@@ -435,7 +435,8 @@ static inline Qcow2BitmapDirEntry
*next_dir_entry(Qcow2BitmapDirEntry *entry)
return (Qcow2BitmapDirEntry *)((uint8_t *)entry + dir_entry_size(entry));
}
-static int check_dir_entry(BlockDriverState *bs, Qcow2BitmapDirEntry *entry)
+static int check_dir_entry(BlockDriverState *bs, Qcow2BitmapDirEntry *entry,
+ bool allow_resize)
{
BDRVQcow2State *s = bs->opaque;
uint64_t phys_bitmap_bytes;
@@ -462,8 +463,14 @@ static int check_dir_entry(BlockDriverState *bs,
Qcow2BitmapDirEntry *entry)
return len;
}
- fail = (phys_bitmap_bytes > BME_MAX_PHYS_SIZE) ||
- (len > ((phys_bitmap_bytes * 8) << entry->granularity_bits));
+ if (phys_bitmap_bytes > BME_MAX_PHYS_SIZE) {
+ return -EINVAL;
+ }
+
+ if (!allow_resize &&
+ (len > ((phys_bitmap_bytes * 8) << entry->granularity_bits))) {
+ return -EINVAL;
+ }
return fail ? -EINVAL : 0;
}
@@ -534,7 +541,8 @@ static uint32_t bitmap_list_count(Qcow2BitmapList *bm_list)
* checks it and convert to bitmap list.
*/
static Qcow2BitmapList *bitmap_list_load(BlockDriverState *bs, uint64_t offset,
- uint64_t size, Error **errp)
+ uint64_t size, bool allow_resize,
+ Error **errp)
{
int ret;
BDRVQcow2State *s = bs->opaque;
@@ -593,7 +601,7 @@ static Qcow2BitmapList *bitmap_list_load(BlockDriverState
*bs, uint64_t offset,
goto fail;
}
- ret = check_dir_entry(bs, e);
+ ret = check_dir_entry(bs, e, allow_resize);
if (ret < 0) {
error_setg(errp, "Bitmap '%.*s' doesn't satisfy the constraints",
e->name_size, dir_entry_name_field(e));
@@ -654,7 +662,7 @@ int qcow2_check_bitmaps_refcounts(BlockDriverState *bs,
BdrvCheckResult *res,
}
bm_list = bitmap_list_load(bs, s->bitmap_directory_offset,
- s->bitmap_directory_size, NULL);
+ s->bitmap_directory_size, false, NULL);
if (bm_list == NULL) {
res->corruptions++;
return -EINVAL;
@@ -755,7 +763,7 @@ static int bitmap_list_store(BlockDriverState *bs,
Qcow2BitmapList *bm_list,
e->extra_data_size = 0;
memcpy(e + 1, bm->name, e->name_size);
- if (check_dir_entry(bs, e) < 0) {
+ if (check_dir_entry(bs, e, false) < 0) {
ret = -EINVAL;
goto fail;
}
@@ -957,7 +965,7 @@ bool qcow2_load_dirty_bitmaps(BlockDriverState *bs, Error
**errp)
}
bm_list = bitmap_list_load(bs, s->bitmap_directory_offset,
- s->bitmap_directory_size, errp);
+ s->bitmap_directory_size, false, errp);
if (bm_list == NULL) {
return false;
}
@@ -1066,7 +1074,7 @@ Qcow2BitmapInfoList
*qcow2_get_bitmap_info_list(BlockDriverState *bs,
}
bm_list = bitmap_list_load(bs, s->bitmap_directory_offset,
- s->bitmap_directory_size, errp);
+ s->bitmap_directory_size, false, errp);
if (bm_list == NULL) {
return NULL;
}
@@ -1111,7 +1119,7 @@ int qcow2_reopen_bitmaps_rw_hint(BlockDriverState *bs,
bool *header_updated,
}
bm_list = bitmap_list_load(bs, s->bitmap_directory_offset,
- s->bitmap_directory_size, errp);
+ s->bitmap_directory_size, false, errp);
if (bm_list == NULL) {
return -EINVAL;
}
@@ -1359,7 +1367,7 @@ void
qcow2_remove_persistent_dirty_bitmap(BlockDriverState *bs,
}
bm_list = bitmap_list_load(bs, s->bitmap_directory_offset,
- s->bitmap_directory_size, errp);
+ s->bitmap_directory_size, false, errp);
if (bm_list == NULL) {
return;
}
@@ -1412,7 +1420,7 @@ void
qcow2_store_persistent_dirty_bitmaps(BlockDriverState *bs, Error **errp)
bm_list = bitmap_list_new();
} else {
bm_list = bitmap_list_load(bs, s->bitmap_directory_offset,
- s->bitmap_directory_size, errp);
+ s->bitmap_directory_size, true, errp);
if (bm_list == NULL) {
return;
}
@@ -1593,7 +1601,7 @@ bool qcow2_can_store_new_dirty_bitmap(BlockDriverState
*bs,
}
bm_list = bitmap_list_load(bs, s->bitmap_directory_offset,
- s->bitmap_directory_size, errp);
+ s->bitmap_directory_size, false, errp);
if (bm_list == NULL) {
goto fail;
}
--
2.17.2
