rpms/qemu
3
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

- Another qcow2 image corruption fix (#496642)

Browse Source
This commit is contained in:
Mark McLoughlin 2009-04-21 09:03:40 +00:00
parent 35588fd688
commit e1eeded4e3
2 changed files with 43 additions and 9 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

47
qemu-fix-qcow2-corruption.patch
View File

@ -1,6 +1,28 @@
From: Nolan Leake <nolan <at> sigbus.net>
Subject: [PATCH] Fix (at least one cause of) qcow2 corruption.
qcow2's get_cluster_offset() scans forward in the l2 table to find other
clusters that have the same allocation status as the first cluster.
This is used by (among others) qcow_is_allocated().
Unfortunately, it was not checking to be sure that it didn't fall off
the end of the l2 table. This patch adds that check.
The symptom that motivated me to look into this was that
bdrv_is_allocated() was returning false when there was in fact data
there. This is one of many ways this bug could lead to data corruption.
I checked the other place that scans for consecutive unallocated blocks
(alloc_cluster_offset()) and it appears to be OK:
nb_clusters = MIN(nb_clusters, s->l2_size - l2_index);
appears to prevent the same problem from occurring.
Signed-off-by: Nolan Leake <nolan <at> sigbus.net>
---
From: Kevin Wolf <kwolf@redhat.com>
To: qemu-devel@nongnu.org
Subject: [Qemu-devel] [PATCH] qcow2 corruption: Fix alloc_cluster_link_l2
Subject: [PATCH] qcow2 corruption: Fix alloc_cluster_link_l2
This patch fixes a qcow2 corruption bug introduced in SVN Rev 5861. L2 tables
are big endian, so entries must be converted before being passed to functions.
@ -18,14 +40,23 @@ qcow2 image (the header is gone after three loop iterations):
done
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
block-qcow2.c | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)
diff -up qemu-kvm-0.10/qemu/block-qcow2.c.qcow2-corruption qemu-kvm-0.10/qemu/block-qcow2.c
--- qemu-kvm-0.10/qemu/block-qcow2.c.qcow2-corruption 2009-04-20 14:41:22.000000000 +0100
+++ qemu-kvm-0.10/qemu/block-qcow2.c 2009-04-20 14:41:54.000000000 +0100
@@ -912,7 +912,7 @@ static int alloc_cluster_link_l2(BlockDr
diff -up qemu-kvm-0.10/qemu/block-qcow2.c.qcow2-corruption qemu-kvm-0.10/qemu/block-qcow2.c
--- qemu-kvm-0.10/qemu/block-qcow2.c.qcow2-corruption 2009-04-21 09:57:21.000000000 +0100
+++ qemu-kvm-0.10/qemu/block-qcow2.c 2009-04-21 09:58:27.000000000 +0100
@@ -670,6 +670,10 @@ static uint64_t get_cluster_offset(Block
nb_available = (nb_available >> 9) + index_in_cluster;
+ if (nb_needed > nb_available) {
+ nb_needed = nb_available;
+ }
+
cluster_offset = 0;
/* seek the the l2 offset in the l1 table */
@@ -912,7 +916,7 @@ static int alloc_cluster_link_l2(BlockDr
goto err;
for (i = 0; i < j; i++)

5
qemu.spec
View File

@ -1,7 +1,7 @@
Summary: QEMU is a FAST! processor emulator
Name: qemu
Version: 0.10
Release: 11%{?dist}
Release: 12%{?dist}
# I have mistakenly thought the revision name would be 1.0.
# So 0.10 series get Epoch = 1
Epoch: 2
@ -467,6 +467,9 @@ fi
%{_mandir}/man1/qemu-img.1*
%changelog
* Tue Apr 21 2009 Mark McLoughlin <markmc@redhat.com> - 2:0.10-12
- Another qcow2 image corruption fix (#496642)
* Mon Apr 20 2009 Mark McLoughlin <markmc@redhat.com> - 2:0.10-11
- Fix qcow2 image corruption (#496642)