Blame SOURCES/kvm-qcow2-Fix-refcount-blocks-beyond-image-end.patch

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From 707d22d6fe9d2f43d0372472b62d40ddb652385d Mon Sep 17 00:00:00 2001
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From: Max Reitz <mreitz@redhat.com>
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Date: Sat, 13 Jun 2015 16:22:20 +0200
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Subject: [PATCH 26/42] qcow2: Fix refcount blocks beyond image end
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Message-id: <1434212556-3927-27-git-send-email-mreitz@redhat.com>
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Patchwork-id: 66045
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O-Subject: [RHEL-7.2 qemu-kvm PATCH 26/42] qcow2: Fix refcount blocks beyond image end
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Bugzilla: 1129893
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RH-Acked-by: Jeffrey Cody <jcody@redhat.com>
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RH-Acked-by: Fam Zheng <famz@redhat.com>
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RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
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BZ: 1129893
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If the qcow2 check function detects a refcount block located beyond the
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image end, grow the image appropriately. This cannot break anything and
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is the logical fix for such a case.
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Signed-off-by: Max Reitz <mreitz@redhat.com>
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Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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(cherry picked from commit 001c158defb65e88e6c50c85d6f20501f7149ddd)
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Signed-off-by: Max Reitz <mreitz@redhat.com>
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Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
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---
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 block/qcow2-refcount.c | 67 +++++++++++++++++++++++++++++++++++++++++++++++---
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 1 file changed, 63 insertions(+), 4 deletions(-)
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diff --git a/block/qcow2-refcount.c b/block/qcow2-refcount.c
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index 8f1215c..8ce0447 100644
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--- a/block/qcow2-refcount.c
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+++ b/block/qcow2-refcount.c
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@@ -1545,7 +1545,7 @@ static int check_refblocks(BlockDriverState *bs, BdrvCheckResult *res,
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                            int64_t *nb_clusters)
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 {
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     BDRVQcowState *s = bs->opaque;
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-    int64_t i;
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+    int64_t i, size;
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     int ret;
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     for(i = 0; i < s->refcount_table_size; i++) {
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@@ -1562,9 +1562,68 @@ static int check_refblocks(BlockDriverState *bs, BdrvCheckResult *res,
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         }
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         if (cluster >= *nb_clusters) {
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-            fprintf(stderr, "ERROR refcount block %" PRId64
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-                    " is outside image\n", i);
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-            res->corruptions++;
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+            fprintf(stderr, "%s refcount block %" PRId64 " is outside image\n",
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+                    fix & BDRV_FIX_ERRORS ? "Repairing" : "ERROR", i);
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+
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+            if (fix & BDRV_FIX_ERRORS) {
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+                int64_t old_nb_clusters = *nb_clusters;
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+                uint16_t *new_refcount_table;
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+
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+                if (offset > INT64_MAX - s->cluster_size) {
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+                    ret = -EINVAL;
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+                    goto resize_fail;
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+                }
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+
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+                ret = bdrv_truncate(bs->file, offset + s->cluster_size);
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+                if (ret < 0) {
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+                    goto resize_fail;
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+                }
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+                size = bdrv_getlength(bs->file);
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+                if (size < 0) {
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+                    ret = size;
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+                    goto resize_fail;
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+                }
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+
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+                *nb_clusters = size_to_clusters(s, size);
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+                assert(*nb_clusters >= old_nb_clusters);
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+
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+                new_refcount_table = g_try_realloc(*refcount_table,
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+                                                   *nb_clusters *
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+                                                   sizeof(**refcount_table));
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+                if (!new_refcount_table) {
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+                    *nb_clusters = old_nb_clusters;
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+                    res->check_errors++;
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+                    return -ENOMEM;
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+                }
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+                *refcount_table = new_refcount_table;
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+
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+                memset(*refcount_table + old_nb_clusters, 0,
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+                       (*nb_clusters - old_nb_clusters) *
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+                       sizeof(**refcount_table));
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+
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+                if (cluster >= *nb_clusters) {
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+                    ret = -EINVAL;
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+                    goto resize_fail;
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+                }
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+
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+                res->corruptions_fixed++;
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+                ret = inc_refcounts(bs, res, refcount_table, nb_clusters,
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+                                    offset, s->cluster_size);
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+                if (ret < 0) {
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+                    return ret;
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+                }
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+                /* No need to check whether the refcount is now greater than 1:
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+                 * This area was just allocated and zeroed, so it can only be
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+                 * exactly 1 after inc_refcounts() */
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+                continue;
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+
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+resize_fail:
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+                res->corruptions++;
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+                fprintf(stderr, "ERROR could not resize image: %s\n",
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+                        strerror(-ret));
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+            } else {
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+                res->corruptions++;
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+            }
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             continue;
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         }
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-- 
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1.8.3.1
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