rxrpc: Fix several cases where a padded len isn't checked in ticket decode
authorDavid Howells <dhowells@redhat.com>
Wed, 14 Jun 2017 23:12:24 +0000 (00:12 +0100)
committerDavid S. Miller <davem@davemloft.net>
Thu, 15 Jun 2017 18:23:44 +0000 (14:23 -0400)
commit5f2f97656ada8d811d3c1bef503ced266fcd53a0
treed119058f42744118b8514c9810c977609bbb26bb
parentf8a894b218138888542a5058d0e902378fd0d4ec
rxrpc: Fix several cases where a padded len isn't checked in ticket decode

This fixes CVE-2017-7482.

When a kerberos 5 ticket is being decoded so that it can be loaded into an
rxrpc-type key, there are several places in which the length of a
variable-length field is checked to make sure that it's not going to
overrun the available data - but the data is padded to the nearest
four-byte boundary and the code doesn't check for this extra.  This could
lead to the size-remaining variable wrapping and the data pointer going
over the end of the buffer.

Fix this by making the various variable-length data checks use the padded
length.

Reported-by: 石磊 <shilei-c@360.cn>
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Marc Dionne <marc.c.dionne@auristor.com>
Reviewed-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
net/rxrpc/key.c