Re: [libvirt] [PATCH for-4.2?] block/qcow2-bitmap: fix crash bug in qcow2_co_remove_persistent_dirty_bitmap

Here is double bug: First, return error but not set errp. This may lead to: qmp block-dirty-bitmap-remove may report success when actually failed block-dirty-bitmap-remove used in a transaction will crash, as qmp_transaction will think that it returned success and will cal

block_dirty_bitmap_remove_commit which will crash, as state->bitmap is NULL Second (like in anecdote), this case is not an error at all. As it is documented in the comment above bdrv_co_remove_persistent_dirty_bitmap definition, absence of bitmap is not an error, and similar case handled at start of qcow2_co_remove_persistent_dirty_bitmap, it returns 0 when there is no bitmaps at all..

But when there are some bitmaps, but not the requested one, it return error with errp unset. Fix that. Fixes: b56a1e31759b750 Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov(a)virtuozzo.com&gt; --- Hi all! Ohm, suddenly we faced this bug. It's a regression in 4.2. I'm very sorry for introducing it, and it sad that it's found so late.. Personally, I think that this one worth rc5, as it makes new bitmap interfaces unusable. But the decision is yours. Last minute edit: hmm, actually, transaction action introduced in 4.2, so crash is not a regression, only broken block-dirty-bitmap-remove command is a regression... Maybe it's OK for stable.

block/qcow2-bitmap.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/block/qcow2-bitmap.c b/block/qcow2-bitmap.c index 8abaf632fc..c6c8ebbe89 100644 --- a/block/qcow2-bitmap.c +++ b/block/qcow2-bitmap.c @@ -1469,8 +1469,10 @@ int coroutine_fn qcow2_co_remove_persistent_dirty_bitmap(BlockDriverState *bs, Qcow2BitmapList *bm_list; if (s->nb_bitmaps == 0) { - /* Absence of the bitmap is not an error: see explanation above - * bdrv_remove_persistent_dirty_bitmap() definition. */ + /* + * Absence of the bitmap is not an error: see explanation above + * bdrv_co_remove_persistent_dirty_bitmap() definition. + */ return 0; } @@ -1485,7 +1487,8 @@ int coroutine_fn qcow2_co_remove_persistent_dirty_bitmap(BlockDriverState *bs, bm = find_bitmap_by_name(bm_list, name); if (bm == NULL) { - ret = -EINVAL; + /* Absence of the bitmap is not an error, see above. */ + ret = 0; goto out; }