vmdk: check l1 size before opening image

L1 table size is calculated from capacity, granularity and l2 table
size. If capacity is too big or later two are too small, the L1 table
will be too big to allocate in memory. Limit it to a reasonable range.

Signed-off-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

diff --git a/block/vmdk.c b/block/vmdk.c
index 53020ef3e3f9070bc22e0e99c315e1204755e39f..955125a7f4fe8690bbf7560ee991ece5744608da 100644 (file)
--- a/block/vmdk.c
+++ b/block/vmdk.c
@@ -597,6 +597,14 @@ static int vmdk_open_vmdk4(BlockDriverState *bs,
     }
     l1_size = (le64_to_cpu(header.capacity) + l1_entry_sectors - 1)
                 / l1_entry_sectors;
+    if (l1_size > 512 * 1024 * 1024) {
+        /* although with big capacity and small l1_entry_sectors, we can get a
+         * big l1_size, we don't want unbounded value to allocate the table.
+         * Limit it to 512M, which is 16PB for default cluster and L2 table
+         * size */
+        error_report("L1 size too big");
+        return -EFBIG;
+    }
     if (le32_to_cpu(header.flags) & VMDK4_FLAG_RGD) {
         l1_backup_offset = le64_to_cpu(header.rgd_offset) << 9;
     }

diff --git a/tests/qemu-iotests/059 b/tests/qemu-iotests/059
index 301eacaf7ee42bf1950003261db2db18155eb12f..b03429dd01037b9f89d8360317165e360c853036 100755 (executable)
--- a/tests/qemu-iotests/059
+++ b/tests/qemu-iotests/059
@@ -43,6 +43,7 @@ _supported_fmt vmdk
 _supported_proto generic
 _supported_os Linux
 
+capacity_offset=16
 granularity_offset=20
 grain_table_size_offset=44
 
@@ -58,6 +59,13 @@ _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
 
+echo "=== Testing too big L1 table size ==="
+echo
+_make_test_img 64M
+poke_file "$TEST_IMG" "$capacity_offset" "\xff\xff\xff\xff"
+poke_file "$TEST_IMG" "$grain_table_size_offset" "\x01\x00\x00\x00"
+{ $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 583955fc7d504daa8a1ccbcb7a2835732d1c6914..9e715e5a95be3326ba8d96d7a2dcff09ae147d4d 100644 (file)
--- a/tests/qemu-iotests/059.out
+++ b/tests/qemu-iotests/059.out
@@ -11,4 +11,10 @@ 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'
+=== Testing too big L1 table size ===
+
+Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864
+L1 size too big
+qemu-io: can't open device TEST_DIR/t.vmdk
+no file open, try 'help open'
 *** done