bridge: Sanitize IFLA_EXT_MASK for AF_BRIDGE:RTM_GETLINK
bridge: Sanitize IFLA_EXT_MASK for AF_BRIDGE:RTM_GETLINK

Only search for IFLA_EXT_MASK if the message actually carries a
ifinfomsg header and validate minimal length requirements for
IFLA_EXT_MASK.

Fixes: 6cbdceeb ("bridge: Dump vlan information from a bridge port")
Cc: Vlad Yasevich <cbd80080413a7dff621bc5de2d3d61903bde20a2@redhat.com>
Signed-off-by: Thomas Graf <17c2d8920621522552b392f72d8fdb4d1e866b44@suug.ch>
Signed-off-by: David S. Miller <fe08d3c717adf2ae63592e4c9aec6e3e404d8e3e@davemloft.net>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs