67 lines
2.6 KiB
Diff
67 lines
2.6 KiB
Diff
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From 84f22c728520792f1010074e0d5ac2ec8e2e372c Mon Sep 17 00:00:00 2001
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From: Maxim Levitsky <mlevitsk@redhat.com>
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Date: Sun, 15 Sep 2019 23:36:53 +0300
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Subject: [PATCH] block/qcow2: Fix corruption introduced by commit 8ac0f15f335
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This fixes subtle corruption introduced by luks threaded encryption
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in commit 8ac0f15f335
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Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1745922
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The corruption happens when we do a write that
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* writes to two or more unallocated clusters at once
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* doesn't fully cover the first sector
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* doesn't fully cover the last sector
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* uses luks encryption
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In this case, when allocating the new clusters we COW both areas
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prior to the write and after the write, and we encrypt them.
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The above mentioned commit accidentally made it so we encrypt the
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second COW area using the physical cluster offset of the first area.
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The problem is that offset_in_cluster in do_perform_cow_encrypt
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can be larger that the cluster size, thus cluster_offset
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will no longer point to the start of the cluster at which encrypted
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area starts.
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Next patch in this series will refactor the code to avoid all these
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assumptions.
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In the bugreport that was triggered by rebasing a luks image to new,
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zero filled base, which lot of such writes, and causes some files
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with zero areas to contain garbage there instead.
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But as described above it can happen elsewhere as well
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Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
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Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
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Message-id: 20190915203655.21638-2-mlevitsk@redhat.com
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Reviewed-by: Max Reitz <mreitz@redhat.com>
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Signed-off-by: Max Reitz <mreitz@redhat.com>
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(cherry picked from commit 38e7d54bdc518b5a05a922467304bcace2396945)
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Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
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---
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block/qcow2-cluster.c | 7 ++++---
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1 file changed, 4 insertions(+), 3 deletions(-)
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diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c
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index cc5609e27a..760564c8fb 100644
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--- a/block/qcow2-cluster.c
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+++ b/block/qcow2-cluster.c
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@@ -473,9 +473,10 @@ static bool coroutine_fn do_perform_cow_encrypt(BlockDriverState *bs,
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assert((offset_in_cluster & ~BDRV_SECTOR_MASK) == 0);
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assert((bytes & ~BDRV_SECTOR_MASK) == 0);
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assert(s->crypto);
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- if (qcow2_co_encrypt(bs, cluster_offset,
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- src_cluster_offset + offset_in_cluster,
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- buffer, bytes) < 0) {
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+ if (qcow2_co_encrypt(bs,
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+ start_of_cluster(s, cluster_offset + offset_in_cluster),
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+ src_cluster_offset + offset_in_cluster,
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+ buffer, bytes) < 0) {
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return false;
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}
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}
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--
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2.23.0
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