diff options
| author | Kevin Wolf <kwolf@redhat.com> | 2014-03-28 18:06:31 +0100 |
|---|---|---|
| committer | Stefan Hajnoczi <stefanha@redhat.com> | 2014-04-01 15:21:03 +0200 |
| commit | b106ad9185f35fc4ad669555ad0e79e276083bd7 (patch) | |
| tree | 180dbb92f35c3299780f066ec023266ab90bc508 /tests/qemu-iotests/080 | |
| parent | 6d33e8e7dc9d40ea105feed4b39caa3e641569e8 (diff) | |
qcow2: Don't rely on free_cluster_index in alloc_refcount_block() (CVE-2014-0147)
free_cluster_index is only correct if update_refcount() was called from
an allocation function, and even there it's brittle because it's used to
protect unfinished allocations which still have a refcount of 0 - if it
moves in the wrong place, the unfinished allocation can be corrupted.
So not using it any more seems to be a good idea. Instead, use the
first requested cluster to do the calculations. Return -EAGAIN if
unfinished allocations could become invalid and let the caller restart
its search for some free clusters.
The context of creating a snapsnot is one situation where
update_refcount() is called outside of a cluster allocation. For this
case, the change fixes a buffer overflow if a cluster is referenced in
an L2 table that cannot be represented by an existing refcount block.
(new_table[refcount_table_index] was out of bounds)
[Bump the qemu-iotests 026 refblock_alloc.write leak count from 10 to
11.
--Stefan]
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Diffstat (limited to 'tests/qemu-iotests/080')
| -rwxr-xr-x | tests/qemu-iotests/080 | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/tests/qemu-iotests/080 b/tests/qemu-iotests/080 index f3091a9377..56f890395c 100755 --- a/tests/qemu-iotests/080 +++ b/tests/qemu-iotests/080 @@ -56,6 +56,8 @@ offset_header_size=100 offset_ext_magic=$header_size offset_ext_size=$((header_size + 4)) +offset_l2_table_0=$((0x40000)) + echo echo "== Huge header size ==" _make_test_img 64M @@ -143,6 +145,15 @@ poke_file "$TEST_IMG" "$offset_backing_file_offset" "\x00\x00\x00\x00\x00\x00\x1 poke_file "$TEST_IMG" "$offset_backing_file_size" "\xff\xff\xff\xff" { $QEMU_IO -c "read 0 512" $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir +echo +echo "== Invalid L2 entry (huge physical offset) ==" +_make_test_img 64M +{ $QEMU_IO -c "write 0 512" $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir +poke_file "$TEST_IMG" "$offset_l2_table_0" "\xbf\xff\xff\xff\xff\xff\x00\x00" +{ $QEMU_IMG snapshot -c test $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir +poke_file "$TEST_IMG" "$offset_l2_table_0" "\x80\x00\x00\xff\xff\xff\x00\x00" +{ $QEMU_IMG snapshot -c test $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir + # success, all done echo "*** done" rm -f $seq.full |