sctp: check policy more carefully when getting pr status

When getting pr_assocstatus and pr_streamstatus by sctp_getsockopt,
it doesn't correctly process the case when policy is set with
SCTP_PR_SCTP_ALL | SCTP_PR_SCTP_MASK. It even causes a
slab-out-of-bounds in sctp_getsockopt_pr_streamstatus().

This patch fixes it by return -EINVAL for this case.

Fixes: 0ac1077e

 ("sctp: get pr_assoc and pr_stream all status with SCTP_PR_SCTP_ALL")
Reported-by:  <syzbot+5da0d0a72a9e7d791748@syzkaller.appspotmail.com>
Suggested-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>