[PATCH 4.19 20/24] sctp: check policy more carefully when getting pr status

[Greg Kroah-Hartman]

4.19-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Xin Long <lucien....@gmail.com>

[ Upstream commit 713358369382cebf92f6e98ce2005f94e7344931 ]

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>
Signed-off-by: David S. Miller <da...@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
 net/sctp/socket.c |    8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -7101,14 +7101,15 @@ static int sctp_getsockopt_pr_assocstatu
        }
 
        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++) {
@@ -7160,7 +7161,8 @@ static int sctp_getsockopt_pr_streamstat
        }
 
        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);