Commit d66e5cee authored by Kevin Wolf's avatar Kevin Wolf
Browse files

qcow1: Stricter backing file length check 



Like qcow2 since commit 6d33e8e7, error out on invalid lengths instead
of silently truncating them to 1023.

Also don't rely on bdrv_pread() catching integer overflows that make len
negative, but use unsigned variables in the first place.

Cc: qemu-stable@nongnu.org
Signed-off-by: default avatarKevin Wolf <kwolf@redhat.com>
Reviewed-by: default avatarBenoit Canet <benoit@irqsave.net>
parent 46485de0

block/qcow.c

+5 −2
Original line number Diff line number Diff line
@@ -97,7 +97,8 @@ static int qcow_open(BlockDriverState *bs, QDict *options, int flags, 
                     Error **errp)

{

    BDRVQcowState *s = bs->opaque;

    int len, i, shift, ret;

    unsigned int len, i, shift;

    int ret;

    QCowHeader header;



    ret = bdrv_pread(bs->file, 0, &header, sizeof(header));
@@ -202,7 +203,9 @@ static int qcow_open(BlockDriverState *bs, QDict *options, int flags, 
    if (header.backing_file_offset != 0) {

        len = header.backing_file_size;

        if (len > 1023) {

            len = 1023;

            error_setg(errp, "Backing file name too long");

            ret = -EINVAL;

            goto fail;

        }

        ret = bdrv_pread(bs->file, header.backing_file_offset,

                   bs->backing_file, len);

tests/qemu-iotests/092

+11 −0
Original line number Diff line number Diff line
@@ -43,6 +43,8 @@ _supported_fmt qcow 
_supported_proto generic

_supported_os Linux



offset_backing_file_offset=8

offset_backing_file_size=16

offset_size=24

offset_cluster_bits=32

offset_l2_bits=33
@@ -81,6 +83,15 @@ poke_file "$TEST_IMG" "$offset_size" "\xee\xee\xee\xee\xee\xee\xee\xee" 
poke_file "$TEST_IMG" "$offset_size" "\x7f\xff\xff\xff\xff\xff\xff\xff"

{ $QEMU_IO -c "write 0 64M" $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir



echo

echo "== Invalid backing file length =="

_make_test_img 64M

poke_file "$TEST_IMG" "$offset_backing_file_offset" "\x00\x00\x00\xff"

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

poke_file "$TEST_IMG" "$offset_backing_file_size" "\x7f\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

tests/qemu-iotests/092.out

+7 −0
Original line number Diff line number Diff line
@@ -28,4 +28,11 @@ qemu-io: can't open device TEST_DIR/t.qcow: Image too large 
no file open, try 'help open'

qemu-io: can't open device TEST_DIR/t.qcow: Image too large

no file open, try 'help open'



== Invalid backing file length ==

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

qemu-io: can't open device TEST_DIR/t.qcow: Backing file name too long

no file open, try 'help open'

qemu-io: can't open device TEST_DIR/t.qcow: Backing file name too long

no file open, try 'help open'

*** done