[Qemu-devel] [PATCH EMBARGOED 6/7] vmdk: check l2 table size when opening

[Fam Zheng <famz@redhat.com>]

header.num_gtes_per_gte determines size for L2 table. Check for too big
value before using it. Limit to 512M entries (2GB per one L2 table).

Signed-off-by: Fam Zheng <famz@redhat.com>
---
 block/vmdk.c               | 5 +++++
 tests/qemu-iotests/059     | 7 +++++++
 tests/qemu-iotests/059.out | 6 ++++++
 3 files changed, 18 insertions(+)

diff --git a/block/vmdk.c b/block/vmdk.c
index 1d6bc39..e28bfc8 100644
--- a/block/vmdk.c
+++ b/block/vmdk.c
@@ -584,6 +584,11 @@ static int vmdk_open_vmdk4(BlockDriverState *bs,
         return -ENOTSUP;
     }
 
+    if (le64_to_cpu(header.num_gtes_per_gte) > 512 * 1024 * 1024) {
+        error_report("L2 table size too big");
+        return -EINVAL;
+    }
+
     l1_entry_sectors = le32_to_cpu(header.num_gtes_per_gte)
                         * le64_to_cpu(header.granularity);
     if (l1_entry_sectors == 0) {
diff --git a/tests/qemu-iotests/059 b/tests/qemu-iotests/059
index f14c41b..aa9eb57 100755
--- a/tests/qemu-iotests/059
+++ b/tests/qemu-iotests/059
@@ -44,6 +44,7 @@ _supported_proto generic
 _supported_os Linux
 
 granularity_offset=20
+grain_table_size_offset=44
 
 echo "=== Testing invalid granularity ==="
 echo
@@ -51,6 +52,12 @@ _make_test_img 64M
 poke_file "$TEST_IMG" "$granularity_offset" "\xff\xff\xff\xff\xff\xff\xff\xff"
 $QEMU_IO -c "read 0 512" $TEST_IMG 2>&1 | _filter_qemu_io | _filter_testdir
 
+echo "=== Testing too big L2 table size ==="
+echo
+_make_test_img 64M
+poke_file "$TEST_IMG" "$grain_table_size_offset" "\xff\xff\xff\xff"
+$QEMU_IO -c "read 0 512" $TEST_IMG 2>&1 | _filter_qemu_io | _filter_testdir
+
 # success, all done
 echo "*** done"
 rm -f $seq.full
diff --git a/tests/qemu-iotests/059.out b/tests/qemu-iotests/059.out
index 380ca3d..583955f 100644
--- a/tests/qemu-iotests/059.out
+++ b/tests/qemu-iotests/059.out
@@ -5,4 +5,10 @@ Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864
 invalid granularity, image may be corrupt
 qemu-io: can't open device TEST_DIR/t.vmdk
 no file open, try 'help open'
+=== Testing too big L2 table size ===
+
+Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864
+L2 table size too big
+qemu-io: can't open device TEST_DIR/t.vmdk
+no file open, try 'help open'
 *** done
-- 
1.8.3.4