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>
diff --git a/lib/nlattr.c b/lib/nlattr.c
index ac09f22..a8408b6 100644
--- a/lib/nlattr.c
+++ b/lib/nlattr.c
@@ -20,6 +20,7 @@
[NLA_U16] = sizeof(u16),
[NLA_U32] = sizeof(u32),
[NLA_U64] = sizeof(u64),
+ [NLA_MSECS] = sizeof(u64),
[NLA_NESTED] = NLA_HDRLEN,
};