9pfs: validate count sent by client with T_readdir
commitd36a5c227099f3f74da27a730350b012b6e99cdd
authorChristian Schoenebeck <qemu_oss@crudebyte.com>
Sat, 8 Feb 2020 08:24:19 +0000 (8 09:24 +0100)
committerGreg Kurz <groug@kaod.org>
Sat, 8 Feb 2020 08:28:54 +0000 (8 09:28 +0100)
treec69044602bbfae2ccc16001ee0fab8b8752dba95
parente16453a31a00c1c0a199cab0617e8aa888f6419a
9pfs: validate count sent by client with T_readdir

A good 9p client sends T_readdir with "count" parameter that's sufficiently
smaller than client's initially negotiated msize (maximum message size).
We perform a check for that though to avoid the server to be interrupted
with a "Failed to encode VirtFS reply type 41" transport error message by
bad clients. This count value constraint uses msize - 11, because 11 is the
header size of R_readdir.

Signed-off-by: Christian Schoenebeck <qemu_oss@crudebyte.com>
Reviewed-by: Greg Kurz <groug@kaod.org>
Message-Id: <3990d3891e8ae2074709b56449e96ab4b4b93b7d.1579567020.git.qemu_oss@crudebyte.com>
[groug: added comment ]
Signed-off-by: Greg Kurz <groug@kaod.org>
hw/9pfs/9p.c