From cf7c49cf6aedb0486ca7ba7c32aa819fe51dadfb Mon Sep 17 00:00:00 2001 From: Eric Blake Date: Wed, 13 Nov 2019 20:46:33 -0600 Subject: [PATCH] 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 Message-Id: <20191114024635.11363-3-eblake@redhat.com> Reviewed-by: Maxim Levitsky Reviewed-by: Vladimir Sementsov-Ogievskiy --- block/dirty-bitmap.c | 12 +++++++++--- block/qcow2-bitmap.c | 2 ++ include/block/dirty-bitmap.h | 2 ++ qapi/block-core.json | 2 +- 4 files changed, 14 insertions(+), 4 deletions(-) diff --git a/block/dirty-bitmap.c b/block/dirty-bitmap.c index 4bbb251b2c..7039e82520 100644 --- 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 ef9ef628a0..809bbc5d20 100644 --- 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 958e7474fb..e2b20ecab9 100644 --- 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 aa97ee2641..0cf68fea14 100644 --- 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