[PATCH net] sctp: check policy more carefully when getting pr status

[Xin Long]

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: 0ac1077e3a54 ("sctp: get pr_assoc and pr_stream all status with 
SCTP_PR_SCTP_ALL")
Reported-by: syzbot+5da0d0a72a9e7d791...@syzkaller.appspotmail.com
Suggested-by: Marcelo Ricardo Leitner <marcelo.leit...@gmail.com>
Signed-off-by: Xin Long <lucien....@gmail.com>
---
 net/sctp/socket.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/net/sctp/socket.c b/net/sctp/socket.c
index fc0386e..739f3e5 100644
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -7083,14 +7083,15 @@ static int sctp_getsockopt_pr_assocstatus(struct sock 
*sk, int len,
        }
 
        policy = params.sprstat_policy;
-       if (!policy || (policy & ~(SCTP_PR_SCTP_MASK | SCTP_PR_SCTP_ALL)))
+       if (!policy || (policy & ~(SCTP_PR_SCTP_MASK | SCTP_PR_SCTP_ALL)) ||
+           ((policy & SCTP_PR_SCTP_ALL) && (policy & SCTP_PR_SCTP_MASK)))
                goto out;
 
        asoc = sctp_id2assoc(sk, params.sprstat_assoc_id);
        if (!asoc)
                goto out;
 
-       if (policy & SCTP_PR_SCTP_ALL) {
+       if (policy == SCTP_PR_SCTP_ALL) {
                params.sprstat_abandoned_unsent = 0;
                params.sprstat_abandoned_sent = 0;
                for (policy = 0; policy <= SCTP_PR_INDEX(MAX); policy++) {
@@ -7142,7 +7143,8 @@ static int sctp_getsockopt_pr_streamstatus(struct sock 
*sk, int len,
        }
 
        policy = params.sprstat_policy;
-       if (!policy || (policy & ~(SCTP_PR_SCTP_MASK | SCTP_PR_SCTP_ALL)))
+       if (!policy || (policy & ~(SCTP_PR_SCTP_MASK | SCTP_PR_SCTP_ALL)) ||
+           ((policy & SCTP_PR_SCTP_ALL) && (policy & SCTP_PR_SCTP_MASK)))
                goto out;
 
        asoc = sctp_id2assoc(sk, params.sprstat_assoc_id);
-- 
2.1.0