block/dmg: validate chunk size to avoid overflow

Previously the chunk size was not checked, allowing for a large memory
allocation. This patch checks whether the chunks size is within the
resource fork length, and whether the resource fork is below the
trailer of the dmg file.

Signed-off-by: Peter Wu <peter@lekensteyn.nl>
Reviewed-by: John Snow <jsnow@redhat.com>
Message-id: 1420566495-13284-6-git-send-email-peter@lekensteyn.nl
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Peter Wu 2015-01-06 18:48:08 +01:00 committed by Kevin Wolf
parent 7aee37b93a
commit f6e6652d7c

View File

@ -317,7 +317,7 @@ static int dmg_read_resource_fork(BlockDriverState *bs, DmgHeaderState *ds,
ret = read_uint32(bs, offset, &count);
if (ret < 0) {
goto fail;
} else if (count == 0) {
} else if (count == 0 || count > info_end - offset) {
ret = -EINVAL;
goto fail;
}
@ -377,6 +377,11 @@ static int dmg_open(BlockDriverState *bs, QDict *options, int flags,
if (ret < 0) {
goto fail;
}
if (rsrc_fork_offset >= offset ||
rsrc_fork_length > offset - rsrc_fork_offset) {
ret = -EINVAL;
goto fail;
}
if (rsrc_fork_length != 0) {
ret = dmg_read_resource_fork(bs, &ds,
rsrc_fork_offset, rsrc_fork_length);