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[Qemu-devel] [PULL for-2.0 25/51] qcow2: Validate refcount table offset
From: |
Stefan Hajnoczi |
Subject: |
[Qemu-devel] [PULL for-2.0 25/51] qcow2: Validate refcount table offset |
Date: |
Tue, 1 Apr 2014 19:19:03 +0200 |
From: Kevin Wolf <address@hidden>
The end of the refcount table must not exceed INT64_MAX so that integer
overflows are avoided.
Also check for misaligned refcount table. Such images are invalid and
probably the result of data corruption. Error out to avoid further
corruption.
Signed-off-by: Kevin Wolf <address@hidden>
Reviewed-by: Max Reitz <address@hidden>
Signed-off-by: Stefan Hajnoczi <address@hidden>
---
block/qcow2.c | 33 +++++++++++++++++++++++++++++++++
tests/qemu-iotests/080 | 13 +++++++++++++
tests/qemu-iotests/080.out | 10 ++++++++++
3 files changed, 56 insertions(+)
diff --git a/block/qcow2.c b/block/qcow2.c
index b9b6e70..37a332f 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -329,6 +329,32 @@ static int qcow2_check(BlockDriverState *bs,
BdrvCheckResult *result,
return ret;
}
+static int validate_table_offset(BlockDriverState *bs, uint64_t offset,
+ uint64_t entries, size_t entry_len)
+{
+ BDRVQcowState *s = bs->opaque;
+ uint64_t size;
+
+ /* Use signed INT64_MAX as the maximum even for uint64_t header fields,
+ * because values will be passed to qemu functions taking int64_t. */
+ if (entries > INT64_MAX / entry_len) {
+ return -EINVAL;
+ }
+
+ size = entries * entry_len;
+
+ if (INT64_MAX - size < offset) {
+ return -EINVAL;
+ }
+
+ /* Tables must be cluster aligned */
+ if (offset & (s->cluster_size - 1)) {
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
static QemuOptsList qcow2_runtime_opts = {
.name = "qcow2",
.head = QTAILQ_HEAD_INITIALIZER(qcow2_runtime_opts.head),
@@ -590,6 +616,13 @@ static int qcow2_open(BlockDriverState *bs, QDict
*options, int flags,
goto fail;
}
+ ret = validate_table_offset(bs, s->refcount_table_offset,
+ s->refcount_table_size, sizeof(uint64_t));
+ if (ret < 0) {
+ error_setg(errp, "Invalid reference count table offset");
+ goto fail;
+ }
+
s->snapshots_offset = header.snapshots_offset;
s->nb_snapshots = header.nb_snapshots;
diff --git a/tests/qemu-iotests/080 b/tests/qemu-iotests/080
index 6179e05..f58ac73 100755
--- a/tests/qemu-iotests/080
+++ b/tests/qemu-iotests/080
@@ -45,6 +45,7 @@ _supported_os Linux
header_size=104
offset_backing_file_offset=8
+offset_refcount_table_offset=48
offset_refcount_table_clusters=56
offset_header_size=100
offset_ext_magic=$header_size
@@ -76,6 +77,18 @@ poke_file "$TEST_IMG" "$offset_refcount_table_clusters"
"\xff\xff\xff\xff"
poke_file "$TEST_IMG" "$offset_refcount_table_clusters" "\x00\x02\x00\x01"
{ $QEMU_IO -c "read 0 512" $TEST_IMG; } 2>&1 | _filter_qemu_io |
_filter_testdir
+echo
+echo "== Misaligned refcount table =="
+_make_test_img 64M
+poke_file "$TEST_IMG" "$offset_refcount_table_offset"
"\x12\x34\x56\x78\x90\xab\xcd\xef"
+{ $QEMU_IO -c "read 0 512" $TEST_IMG; } 2>&1 | _filter_qemu_io |
_filter_testdir
+
+echo
+echo "== Huge refcount offset =="
+_make_test_img 64M
+poke_file "$TEST_IMG" "$offset_refcount_table_offset"
"\xff\xff\xff\xff\xff\xff\x00\x00"
+poke_file "$TEST_IMG" "$offset_refcount_table_clusters" "\x00\x00\x00\x7f"
+{ $QEMU_IO -c "read 0 512" $TEST_IMG; } 2>&1 | _filter_qemu_io |
_filter_testdir
# success, all done
echo "*** done"
diff --git a/tests/qemu-iotests/080.out b/tests/qemu-iotests/080.out
index 6fef6d9..f919b58 100644
--- a/tests/qemu-iotests/080.out
+++ b/tests/qemu-iotests/080.out
@@ -20,4 +20,14 @@ qemu-io: can't open device TEST_DIR/t.qcow2: Reference count
table too large
no file open, try 'help open'
qemu-io: can't open device TEST_DIR/t.qcow2: Reference count table too large
no file open, try 'help open'
+
+== Misaligned refcount table ==
+Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864
+qemu-io: can't open device TEST_DIR/t.qcow2: Invalid reference count table
offset
+no file open, try 'help open'
+
+== Huge refcount offset ==
+Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864
+qemu-io: can't open device TEST_DIR/t.qcow2: Invalid reference count table
offset
+no file open, try 'help open'
*** done
--
1.9.0
- [Qemu-devel] [PULL for-2.0 12/51] bochs: Unify header structs and make them QEMU_PACKED, (continued)
- [Qemu-devel] [PULL for-2.0 12/51] bochs: Unify header structs and make them QEMU_PACKED, Stefan Hajnoczi, 2014/04/01
- [Qemu-devel] [PULL for-2.0 13/51] bochs: Use unsigned variables for offsets and sizes (CVE-2014-0147), Stefan Hajnoczi, 2014/04/01
- [Qemu-devel] [PULL for-2.0 16/51] bochs: Fix bitmap offset calculation, Stefan Hajnoczi, 2014/04/01
- [Qemu-devel] [PULL for-2.0 18/51] vpc: Validate block size (CVE-2014-0142), Stefan Hajnoczi, 2014/04/01
- [Qemu-devel] [PULL for-2.0 17/51] vpc/vhd: add bounds check for max_table_entries and block_size (CVE-2014-0144), Stefan Hajnoczi, 2014/04/01
- [Qemu-devel] [PULL for-2.0 19/51] vdi: add bounds checks for blocks_in_image and disk_size header fields (CVE-2014-0144), Stefan Hajnoczi, 2014/04/01
- [Qemu-devel] [PULL for-2.0 21/51] curl: check data size before memcpy to local buffer. (CVE-2014-0144), Stefan Hajnoczi, 2014/04/01
- [Qemu-devel] [PULL for-2.0 20/51] vhdx: Bounds checking for block_size and logical_sector_size (CVE-2014-0148), Stefan Hajnoczi, 2014/04/01
- [Qemu-devel] [PULL for-2.0 22/51] qcow2: Check header_length (CVE-2014-0144), Stefan Hajnoczi, 2014/04/01
- [Qemu-devel] [PULL for-2.0 23/51] qcow2: Check backing_file_offset (CVE-2014-0144), Stefan Hajnoczi, 2014/04/01
- [Qemu-devel] [PULL for-2.0 25/51] qcow2: Validate refcount table offset,
Stefan Hajnoczi <=
- [Qemu-devel] [PULL for-2.0 24/51] qcow2: Check refcount table size (CVE-2014-0144), Stefan Hajnoczi, 2014/04/01
- [Qemu-devel] [PULL for-2.0 26/51] qcow2: Validate snapshot table offset/size (CVE-2014-0144), Stefan Hajnoczi, 2014/04/01
- [Qemu-devel] [PULL for-2.0 27/51] qcow2: Validate active L1 table offset and size (CVE-2014-0144), Stefan Hajnoczi, 2014/04/01
- [Qemu-devel] [PULL for-2.0 28/51] qcow2: Fix backing file name length check, Stefan Hajnoczi, 2014/04/01
- [Qemu-devel] [PULL for-2.0 29/51] qcow2: Don't rely on free_cluster_index in alloc_refcount_block() (CVE-2014-0147), Stefan Hajnoczi, 2014/04/01
- [Qemu-devel] [PULL for-2.0 30/51] qcow2: Avoid integer overflow in get_refcount (CVE-2014-0143), Stefan Hajnoczi, 2014/04/01
- [Qemu-devel] [PULL for-2.0 31/51] qcow2: Check new refcount table size on growth, Stefan Hajnoczi, 2014/04/01
- [Qemu-devel] [PULL for-2.0 35/51] dmg: coding style and indentation cleanup, Stefan Hajnoczi, 2014/04/01
- [Qemu-devel] [PULL for-2.0 36/51] dmg: prevent out-of-bounds array access on terminator, Stefan Hajnoczi, 2014/04/01
- [Qemu-devel] [PULL for-2.0 34/51] qcow2: Fix new L1 table size check (CVE-2014-0143), Stefan Hajnoczi, 2014/04/01