vduse: check that offset is within bounds in get_config()
authorDan Carpenter <dan.carpenter@oracle.com>
Wed, 8 Dec 2021 15:09:56 +0000 (18:09 +0300)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Wed, 22 Dec 2021 08:32:36 +0000 (09:32 +0100)
commitebbbc5fea3f648175df1aa3f127c78eb0252cc2a
treee3caf65dea3f06b3aee95d70d97f582892923d9d
parente6c67560b4341914bec32ec536e931c22062af65
vduse: check that offset is within bounds in get_config()

commit dc1db0060c02d119fd4196924eff2d1129e9a442 upstream.

This condition checks "len" but it does not check "offset" and that
could result in an out of bounds read if "offset > dev->config_size".
The problem is that since both variables are unsigned the
"dev->config_size - offset" subtraction would result in a very high
unsigned value.

I think these checks might not be necessary because "len" and "offset"
are supposed to already have been validated using the
vhost_vdpa_config_validate() function.  But I do not know the code
perfectly, and I like to be safe.

Fixes: c8a6153b6c59 ("vduse: Introduce VDUSE - vDPA Device in Userspace")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Link: https://lore.kernel.org/r/20211208150956.GA29160@kili
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
drivers/vdpa/vdpa_user/vduse_dev.c