Commit c30bc947 authored Nov 03, 2011 by Johannes Berg Committed by David S. Miller Nov 04, 2011

netlink: validate NLA_MSECS length



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>
Cc: stable@vger.kernel.org
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent 433aee04

lib/nlattr.c

+1 −0

Original line number	Diff line number	Diff line
		@@ -20,6 +20,7 @@ static const u16 nla_attr_minlen[NLA_TYPE_MAX+1] = {
		[NLA_U16] = sizeof(u16),
		[NLA_U32] = sizeof(u32),
		[NLA_U64] = sizeof(u64),
		[NLA_MSECS] = sizeof(u64),
		[NLA_NESTED] = NLA_HDRLEN,
		};