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[Qemu-block] [PATCH v3 8/8] block/qcow2-refcount: fix out-of-file L2 ent
From: |
Vladimir Sementsov-Ogievskiy |
Subject: |
[Qemu-block] [PATCH v3 8/8] block/qcow2-refcount: fix out-of-file L2 entries |
Date: |
Thu, 11 Oct 2018 18:16:23 +0300 |
Rewrite corrupted L2 table entry, which reference space out of
underlying file.
Signed-off-by: Vladimir Sementsov-Ogievskiy <address@hidden>
---
block/qcow2-refcount.c | 66 +++++++++++++++++++++++++++++++++++++++++-
1 file changed, 65 insertions(+), 1 deletion(-)
diff --git a/block/qcow2-refcount.c b/block/qcow2-refcount.c
index 5ebe292fc1..2e2ba806ed 100644
--- a/block/qcow2-refcount.c
+++ b/block/qcow2-refcount.c
@@ -1629,11 +1629,37 @@ static int check_refcounts_l2(BlockDriverState *bs,
BdrvCheckResult *res,
int flags, BdrvCheckMode fix, bool active)
{
BDRVQcow2State *s = bs->opaque;
- uint64_t *l2_table;
+ uint64_t *l2_table, zero_fix_entry;
uint64_t next_contiguous_offset = 0;
int i, l2_size, ret;
bool fix_er = fix & BDRV_FIX_ERRORS;
RepTableType type = active ? REP_ACTIVE_L2 : REP_INACTIVE_L2;
+ const char *zero_fix_desc = "";
+ int64_t file_len = bdrv_getlength(bs->file->bs);
+
+ if (file_len < 0) {
+ return file_len;
+ }
+
+ if (fix_er) {
+ /* prepare options for fixing corrupted l2 entries to be marked as zero
+ * or unallocated
+ */
+ if (s->qcow_version >= 3) {
+ zero_fix_entry = QCOW_OFLAG_ZERO;
+ zero_fix_desc = ": mark cluster as zero";
+ } else {
+ /* v2 doesn't support ZERO flag, so we just mark it unallocated.
+ * It's a bit unsafe, as backing file may become available through
+ * the hole. However, discard for v2 do the same, so we don't care
+ * too.
+ */
+ zero_fix_entry = 0;
+ zero_fix_desc = ": mark cluster as unallocated (warning: "
+ "underlying backing file may become available "
+ "through the hole)";
+ }
+ }
/* Read L2 table from disk */
l2_size = s->l2_size * sizeof(uint64_t);
@@ -1670,6 +1696,34 @@ static int check_refcounts_l2(BlockDriverState *bs,
BdrvCheckResult *res,
offset = l2_entry & s->cluster_offset_mask & ~511;
size = (((l2_entry >> s->csize_shift) & s->csize_mask) + 1) * 512;
+
+ if (offset + size > QEMU_ALIGN_UP(file_len, 512)) {
+ /* The compressed data does not necessarily occupy
+ * all of the bytes in the final 512-bytes sector
+ */
+ const char *fix_desc = "";
+ uint64_t orig_size = size;
+ fatal = true;
+
+ if (fix_er) {
+ if (offset < file_len) {
+ size = QEMU_ALIGN_UP(file_len, 512) - offset;
+ l2_entry_fix &=
+ ~((uint64_t)s->csize_mask << s->csize_shift);
+ l2_entry_fix |= (size / 512 - 1) << s->csize_shift;
+ fix_desc = ": try to fix cluster size";
+ } else {
+ l2_entry_fix = zero_fix_entry;
+ fix_desc = zero_fix_desc;
+ }
+ } else {
+ res->corruptions++;
+ }
+ fprintf(stderr, "%s: compressed cluster out of file: "
+ "offset 0x%" PRIx64 " size 0x%" PRIx64 "%s\n",
+ fix_er ? "Repairing" : "ERROR",
+ offset, orig_size, fix_desc);
+ }
break;
case QCOW2_CLUSTER_ZERO_ALLOC:
@@ -1677,6 +1731,16 @@ static int check_refcounts_l2(BlockDriverState *bs,
BdrvCheckResult *res,
offset = l2_entry & L2E_OFFSET_MASK;
size = s->cluster_size;
+ if (offset >= file_len) {
+ fatal = true; /* for sure, there is no allocation after EOF */
+ fprintf(stderr,
+ "%s: cluster out of file: offset 0x%" PRIx64 "%s\n",
+ fix_er ? "Repairing" : "ERROR", offset,
+ fix_er ? zero_fix_desc : "");
+ l2_entry_fix = zero_fix_entry;
+ break;
+ }
+
/* Correct offsets are cluster aligned */
if (offset_into_cluster(s, offset)) {
fatal = true; /* misaligned cluster leads to
--
2.18.0
- [Qemu-block] [PATCH v3 0/8] qcow2 check improvements, Vladimir Sementsov-Ogievskiy, 2018/10/11
- [Qemu-block] [PATCH v3 2/8] block/qcow2-refcount: avoid eating RAM, Vladimir Sementsov-Ogievskiy, 2018/10/11
- [Qemu-block] [PATCH v3 3/8] block/qcow2-refcount: check_refcounts_l2: refactor compressed case, Vladimir Sementsov-Ogievskiy, 2018/10/11
- [Qemu-block] [PATCH v3 8/8] block/qcow2-refcount: fix out-of-file L2 entries,
Vladimir Sementsov-Ogievskiy <=
- [Qemu-block] [PATCH v3 7/8] block/qcow2-refcount: fix out-of-file L1 entries to be zero, Vladimir Sementsov-Ogievskiy, 2018/10/11
- [Qemu-block] [PATCH v3 5/8] block/qcow2-refcount: check_refcounts_l2: don't count corrupted entries, Vladimir Sementsov-Ogievskiy, 2018/10/11
- [Qemu-block] [PATCH v3 1/8] block/qcow2-refcount: fix check_oflag_copied, Vladimir Sementsov-Ogievskiy, 2018/10/11
- [Qemu-block] [PATCH v3 4/8] block/qcow2-refcount: check_refcounts_l2: reduce ignored overlaps, Vladimir Sementsov-Ogievskiy, 2018/10/11
- [Qemu-block] [PATCH v3 6/8] block/qcow2-refcount: refactor fixing L2 entry, Vladimir Sementsov-Ogievskiy, 2018/10/11