On 13.09.19 00:37, Maxim Levitsky wrote: > This fixes subtle corruption introduced by luks threaded encryption > in commit 8ac0f15f335 > > Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1745922 > > The corruption happens when we do a write that > * writes to two or more unallocated clusters at once > * doesn't fully cover the first sector > * doesn't fully cover the last sector > > In this case, when allocating the new clusters we COW both areas > prior to the write and after the write, and we encrypt them. > > The above mentioned commit accidentally made it so we encrypt the > second COW area using the physical cluster offset of the first area. > > Fix this by: > * Remove the offset_in_cluster parameter of do_perform_cow_encrypt, > since it is misleading. That offset can be larger than cluster size > currently. > > Instead just add the start and the end COW area offsets to both host > and guest offsets that do_perform_cow_encrypt receives. > > * in do_perform_cow_encrypt, remove the cluster offset from the host_offset, > and thus pass correctly to the qcow2_co_encrypt, the host cluster offset > and full guest offset > > In the bugreport that was triggered by rebasing a luks image to new, > zero filled base, which lot of such writes, and causes some files > with zero areas to contain garbage there instead. > But as described above it can happen elsewhere as well > > > Signed-off-by: Maxim Levitsky <mlevi...@redhat.com> > Reviewed-by: Vladimir Sementsov-Ogievskiy <vsement...@virtuozzo.com> > --- > block/qcow2-cluster.c | 29 +++++++++++++++++------------ > 1 file changed, 17 insertions(+), 12 deletions(-)
Reviewed-by: Max Reitz <mre...@redhat.com>
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