qcow2: Check snapshot L1 tables in qcow2_check_metadata_overlap()

The inactive-l2 overlap check iterates uses the L1 tables from all
snapshots, but it does not validate them first.

We now have a function to take care of this, so let's use it.
Signed-off-by: NAlberto Garcia <berto@igalia.com>
Reviewed-by: NEric Blake <eblake@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

block/qcow2-refcount.c

@@ -2642,9 +2642,17 @@ int qcow2_check_metadata_overlap(BlockDriverState *bs, int ign, int64_t offset,
             uint64_t l1_ofs = s->snapshots[i].l1_table_offset;
             uint32_t l1_sz  = s->snapshots[i].l1_size;
             uint64_t l1_sz2 = l1_sz * sizeof(uint64_t);
-            uint64_t *l1 = g_try_malloc(l1_sz2);
+            uint64_t *l1;
             int ret;
 
+            ret = qcow2_validate_table(bs, l1_ofs, l1_sz, sizeof(uint64_t),
+                                       QCOW_MAX_L1_SIZE, "", NULL);
+            if (ret < 0) {
+                return ret;
+            }
+
+            l1 = g_try_malloc(l1_sz2);
+
             if (l1_sz2 && l1 == NULL) {
                 return -ENOMEM;
             }

tests/qemu-iotests/080

@@ -178,6 +178,8 @@ _make_test_img 64M
 poke_file "$TEST_IMG" "$offset_snap1_l1_offset" "\x00\x00\x00\x00\x00\x40\x02\x00"
 { $QEMU_IMG convert -s test $TEST_IMG $TEST_IMG.snap; } 2>&1 | _filter_testdir
 { $QEMU_IMG amend -o compat=0.10 $TEST_IMG; } 2>&1 | _filter_testdir
+{ $QEMU_IO -c "open -o overlap-check.inactive-l2=on $TEST_IMG" \
+           -c 'write 0 4k'; } 2>&1 | _filter_qemu_io | _filter_testdir
 
 echo
 echo "== Invalid snapshot L1 table size =="
@@ -187,6 +189,8 @@ _make_test_img 64M
 poke_file "$TEST_IMG" "$offset_snap1_l1_size" "\x10\x00\x00\x00"
 { $QEMU_IMG convert -s test $TEST_IMG $TEST_IMG.snap; } 2>&1 | _filter_testdir
 { $QEMU_IMG amend -o compat=0.10 $TEST_IMG; } 2>&1 | _filter_testdir
+{ $QEMU_IO -c "open -o overlap-check.inactive-l2=on $TEST_IMG" \
+           -c 'write 0 4k'; } 2>&1 | _filter_qemu_io | _filter_testdir
 
 # success, all done
 echo "*** done"

tests/qemu-iotests/080.out

@@ -66,6 +66,8 @@ wrote 512/512 bytes at offset 0
 qemu-img: Failed to load snapshot: Snapshot L1 table offset invalid
 qemu-img: Snapshot L1 table offset invalid
 qemu-img: Error while amending options: Invalid argument
+Failed to flush the refcount block cache: Invalid argument
+write failed: Invalid argument
 
 == Invalid snapshot L1 table size ==
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864
@@ -74,4 +76,6 @@ wrote 512/512 bytes at offset 0
 qemu-img: Failed to load snapshot: Snapshot L1 table too large
 qemu-img: Snapshot L1 table too large
 qemu-img: Error while amending options: File too large
+Failed to flush the refcount block cache: File too large
+write failed: File too large
 *** done