netlink: validate NLA_MSECS length
authorJohannes Berg <johannes.berg@intel.com>
Thu, 3 Nov 2011 00:07:32 +0000 (00:07 +0000)
committerGreg Kroah-Hartman <gregkh@suse.de>
Fri, 11 Nov 2011 17:44:43 +0000 (09:44 -0800)
commit61ec3a5696f0c32448c93b713f934b007b85f961
tree457b77f5305517b77e732e5335bd4cd823cdedd2
parent0fb9f687964a4b4a557b4f2e8676e1236a9e269b
netlink: validate NLA_MSECS length

commit c30bc94758ae2a38a5eb31767c1985c0aae0950b upstream.

L2TP for example uses NLA_MSECS like this:
policy:
        [L2TP_ATTR_RECV_TIMEOUT]        = { .type = NLA_MSECS, },
code:
        if (info->attrs[L2TP_ATTR_RECV_TIMEOUT])
                cfg.reorder_timeout = nla_get_msecs(info->attrs[L2TP_ATTR_RECV_TIMEOUT]);

As nla_get_msecs() is essentially nla_get_u64() plus the
conversion to a HZ-based value, this will not properly
reject attributes from userspace that aren't long enough
and might overrun the message.

Add NLA_MSECS to the attribute minlen array to check the
size properly.

Cc: Thomas Graf <tgraf@suug.ch>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
lib/nlattr.c