Commit 2d51c32c authored by Kevin Wolf's avatar Kevin Wolf Committed by Stefan Hajnoczi
Browse files

qcow2: Validate active L1 table offset and size (CVE-2014-0144) 



This avoids an unbounded allocation.

Signed-off-by: default avatarKevin Wolf <kwolf@redhat.com>
Reviewed-by: default avatarMax Reitz <mreitz@redhat.com>
Signed-off-by: default avatarStefan Hajnoczi <stefanha@redhat.com>
parent ce48f2f4

block/qcow2.c

+16 −0
Original line number Diff line number Diff line
@@ -642,6 +642,13 @@ static int qcow2_open(BlockDriverState *bs, QDict *options, int flags, 
    s->nb_snapshots = header.nb_snapshots;



    /* read the level 1 table */

    if (header.l1_size > 0x2000000) {

        /* 32 MB L1 table is enough for 2 PB images at 64k cluster size

         * (128 GB for 512 byte clusters, 2 EB for 2 MB clusters) */

        error_setg(errp, "Active L1 table too large");

        ret = -EFBIG;

        goto fail;

    }

    s->l1_size = header.l1_size;



    l1_vm_state_index = size_to_l1(s, header.size);
@@ -659,7 +666,16 @@ static int qcow2_open(BlockDriverState *bs, QDict *options, int flags, 
        ret = -EINVAL;

        goto fail;

    }



    ret = validate_table_offset(bs, header.l1_table_offset,

                                header.l1_size, sizeof(uint64_t));

    if (ret < 0) {

        error_setg(errp, "Invalid L1 table offset");

        goto fail;

    }

    s->l1_table_offset = header.l1_table_offset;





    if (s->l1_size > 0) {

        s->l1_table = g_malloc0(

            align_offset(s->l1_size * sizeof(uint64_t), 512));

tests/qemu-iotests/080

+18 −0
Original line number Diff line number Diff line
@@ -45,6 +45,8 @@ _supported_os Linux 
header_size=104



offset_backing_file_offset=8

offset_l1_size=36

offset_l1_table_offset=40

offset_refcount_table_offset=48

offset_refcount_table_clusters=56

offset_nb_snapshots=60
@@ -117,6 +119,22 @@ poke_file "$TEST_IMG" "$offset_nb_snapshots" "\x00\x01\x00\x00" 
{ $QEMU_IMG snapshot -c test $TEST_IMG; } 2>&1 | _filter_testdir

{ $QEMU_IO -c "read 0 512" $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir



echo

echo "== Invalid L1 table =="

_make_test_img 64M

poke_file "$TEST_IMG" "$offset_l1_size" "\xff\xff\xff\xff"

{ $QEMU_IO -c "read 0 512" $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir

poke_file "$TEST_IMG" "$offset_l1_size" "\x7f\xff\xff\xff"

{ $QEMU_IO -c "read 0 512" $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir



poke_file "$TEST_IMG" "$offset_l1_table_offset" "\x7f\xff\xff\xff\xff\xff\x00\x00"

poke_file "$TEST_IMG" "$offset_l1_size" "\x00\x00\xff\xff"

{ $QEMU_IO -c "read 0 512" $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir



poke_file "$TEST_IMG" "$offset_l1_table_offset" "\x12\x34\x56\x78\x90\xab\xcd\xef"

poke_file "$TEST_IMG" "$offset_l1_size" "\x00\x00\x00\x01"

{ $QEMU_IO -c "read 0 512" $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir



# success, all done

echo "*** done"

rm -f $seq.full

tests/qemu-iotests/080.out

+11 −0
Original line number Diff line number Diff line
@@ -47,4 +47,15 @@ Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864 
qemu-img: Could not create snapshot 'test': -27 (File too large)

read 512/512 bytes at offset 0

512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)



== Invalid L1 table ==

Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864 

qemu-io: can't open device TEST_DIR/t.qcow2: Active L1 table too large

no file open, try 'help open'

qemu-io: can't open device TEST_DIR/t.qcow2: Active L1 table too large

no file open, try 'help open'

qemu-io: can't open device TEST_DIR/t.qcow2: Invalid L1 table offset

no file open, try 'help open'

qemu-io: can't open device TEST_DIR/t.qcow2: Invalid L1 table offset

no file open, try 'help open'

*** done