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[PATCH for-4.2?] block/qcow2-bitmap: fix crash bug in qcow2_co_remove_pe
From: |
Vladimir Sementsov-Ogievskiy |
Subject: |
[PATCH for-4.2?] block/qcow2-bitmap: fix crash bug in qcow2_co_remove_persistent_dirty_bitmap |
Date: |
Thu, 5 Dec 2019 22:30:49 +0300 |
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 <address@hidden>
---
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;
}
--
2.21.0
- [PATCH for-4.2?] block/qcow2-bitmap: fix crash bug in qcow2_co_remove_persistent_dirty_bitmap,
Vladimir Sementsov-Ogievskiy <=
- Re: [PATCH for-4.2?] block/qcow2-bitmap: fix crash bug in qcow2_co_remove_persistent_dirty_bitmap, John Snow, 2019/12/05
- Re: [PATCH for-4.2?] block/qcow2-bitmap: fix crash bug in qcow2_co_remove_persistent_dirty_bitmap, Eric Blake, 2019/12/05
- Re: [PATCH for-4.2?] block/qcow2-bitmap: fix crash bug in qcow2_co_remove_persistent_dirty_bitmap, John Snow, 2019/12/05
- Re: [PATCH for-4.2?] block/qcow2-bitmap: fix crash bug in qcow2_co_remove_persistent_dirty_bitmap, Vladimir Sementsov-Ogievskiy, 2019/12/06
- Re: [PATCH for-4.2?] block/qcow2-bitmap: fix crash bug in qcow2_co_remove_persistent_dirty_bitmap, Eric Blake, 2019/12/06
- Re: [PATCH for-4.2?] block/qcow2-bitmap: fix crash bug in qcow2_co_remove_persistent_dirty_bitmap, John Snow, 2019/12/06
- Re: [PATCH for-4.2?] block/qcow2-bitmap: fix crash bug in qcow2_co_remove_persistent_dirty_bitmap, Eric Blake, 2019/12/06
Re: [PATCH for-4.2?] block/qcow2-bitmap: fix crash bug in qcow2_co_remove_persistent_dirty_bitmap, Vladimir Sementsov-Ogievskiy, 2019/12/06